Hue–Da Nang Campaign

The Hue–Da Nang Campaign was a series of military actions conducted by the Vietnam People's Army (VPA) and the Viet Cong against the Army of the Republic of Vietnam (ARVN) during the Vietnam War, also known in Vietnam as the American War. The campaign was centred on the cities of Huế (Thừa Thiên–Huế Province) and Da Nang (Quảng Nam Province), with secondary fronts in the provinces of Quảng Trị and Quảng Ngãi. The campaign began on March 5 and concluded on April 2, 1975.

During the spring season of 1975, the Vietnam People's Army High Command in Hanoi made the decision to seize the major South Vietnamese cities of Huế and Da Nang, and also destroy the various South Vietnamese units in I Corps Tactical Zone, led by ARVN General Ngo Quang Truong. Originally, the campaign was planned to take place over two phases; during the seasons of spring-summer and autumn. However, as the North Vietnamese and Viet Cong forces rolled over South Vietnamese defences on the outskirts of Huế and Da Nang, President Nguyễn Văn Thiệu ordered General Truong to abandon all territories under his control, and pull his forces back to the coastal areas of I Corps. However, the South Vietnamese withdrawal quickly turned into a rout, as the North Vietnamese 2nd Army Corps picked off one South Vietnamese unit after another, until Huế and Da Nang was completely surrounded. By March 29, 1975, North Vietnamese troops had full control of Huế and Da Nang, while South Vietnam lost all territories in I Corps and most of the units belonging to the ARVN 1st Brigade.

The fall of Huế and Da Nang did not spell the end of the misery suffered by the Army of the Republic of Vietnam. On March 31, ARVN General Pham Van Phu—commander of II Corps Tactical Zone—attempted to form a new defensive line from Qui Nhơn to cover the retreat of the ARVN 22nd Infantry Division into the Mekong Delta, but they too were destroyed by the North Vietnamese. By April 2, South Vietnam had lost control of the northern provinces, as well as two army corps.

North Vietnam
During the Huế–Da Nang Campaign of 1975, North Vietnamese and Viet Cong forces were organised into three formations; the Vietnam People's Army 2nd Corps, Tri Thien Military Zone, and Military Region 5 Command. The 2nd Corps of the Vietnam People's Army fielded three infantry divisions (304th, 324th and 324th Divisions), the 673rd Air-Defence Division, the 164th Artillery Brigade, the 203rd Armoured Regiment, the 219th Combat Engineers Brigade, and the 463rd Communications Regiment. The 2nd Corps was led by Major-General Nguyen Huu An, with Major-General Le Linh as Political Commissar. Colonel Hoang Dan was the deputy commander, and Colonel Nguyen Cong Trang was the deputy political commissar.

Led by Brigadier-General Le Tu Dong, the Tri Thien Military Zone had three infantry regiments (4th, 46th and 271st Regiments), and two battalions (the 21st Independent Battalion and the 6th Local Force Battalion). Military Region 5 had one infantry division (2nd Division), which was supported by the 141st Regiment (from the 3rd ‘Gold Star’ Division), the 52nd Independent Brigade, two artillery regiments (368th and 572nd Artillery Regiments), two local battalions (70th and 72nd Local Force Battalions), and two local regiments (94th and 96th Local Force Regiments). North Vietnamese and Viet Cong units of Military Region 5 were placed under the responsibility of Major-General Chu Huy Man, with Vo Chi Cong as political commissar.

Tri Thien
On February 21, 1975, North Vietnamese field commanders from Tri-Thien Military Zone and the 2nd Army Corp held a conference to establish their objectives, which were planned to occur in two phases; the spring-summer phase that would begin in March and probably conclude in May, and the autumn phase to last from July to August 1975. The North Vietnamese objective was to take control of Quảng Trị Province, isolate the city of Huế and if the opportunity presents itself, they would capture the entire Tri Thien-Huế area. To isolate Huế, the North Vietnamese 2nd Army Corps would move against their target from the north-west direction along Route 12 down to the south-west along Highway 14, thereby isolating the region from South Vietnamese forces in II Corps Tactical Zone.

In preparation for the Huế–Da Nang Campaign, the North Vietnamese 2nd Army Corps had successfully captured several important base areas that surrounded South Vietnamese units in Quảng Trị Province and Thừa Thiên Province. Those areas included Dong Ha-Ai Tu to the north, Khe Sanh-Ba Long to the west, and A Luoi-Nam Dong in southern Huế. The main body of the 304th Division and the 3rd Regiment, 324th Division, had assembled in Nong Son and Thuong Duc to attack Da Nang from the west. In Military Region 5, the 2nd Division had established its positions in Tien Phuoc, Tra My and Trà Bồng in Quảng Ngãi Province, and Đắk Tô and Tan Canh in Kon Tum Province.

Quảng Nam-Quảng Ngãi
Once Huế had been isolated, Military Region 5 Command would initiate the Nam-Ngai Campaign from the provinces of Quảng Nam and Quảng Ngãi, to isolate Da Nang from the Central Highlands. North Vietnamese units such as the 2nd Division, the 141st Regiment, the 52nd Brigade, along with two artillery regiments (368th and 572nd Artillery Regiments) would coordinate their efforts with the Viet Cong 94th and 96th Local Force Regiments, and the 70th and 72nd Local Force Battalions. As part of their overall objective, they would tie down the ARVN 2nd Infantry Division, the 11th Armoured Squadron and the 912th Regional Force Company in Quảng Ngãi Province. And, if the opportunity arises, they would also capture Bình Định Province and the city of Quy Nhon.

Da Nang
In the final phase of their operation, the North Vietnamese and Viet Cong would cut off Da Nang from the surrounding regions which made up I Corps Tactical Zone, and prevent reinforcements from retaking the city. Then, depending on the situation, the North Vietnamese would organise an attack to capture the major South Vietnamese army, navy and air force installations in Da Nang.

South Vietnam
South Vietnamese military forces in Huế and Da Nang belonged to the ARVN 1st Brigade, I Corps Tactical Zone. Commanded by Lieutenant General Ngo Quang Truong, the South Vietnamese I Corps was considered to be the strongest amongst all the military formations of South Vietnam. It had three infantry divisions (1st, 2nd and 3rd Infantry Divisions), the Airborne Division (led by Major General Le Quang Luong), the Marine Corps Division (led by Major General Bui The Lan), and four ranger groups (11th, 12th, 14th and 15th Ranger Groups). The Airborne and Marine Corps Division each had an assigned strength of four brigades. In addition to the infantry units, there were also the 5th Armoured Brigade, five squadrons of armoured vehicles (4th, 7th, 11th, 17th and 20th Armoured Squadrons), 13 armoured companies, and 21 artillery battalions.

Local defence in I Corps was provided by 50 battalions and five companies of Regional and Popular Forces, and six companies of military police. Support for ground forces in the area came in the form of the 1st Air Force Division (commanded by Brigadier-General Nguyen Van Khanh), with two naval squadrons operating on the coast and another two along the rivers. Overall, I Corps fielded about 134,000 soldiers; 84,000 were regular soldiers and 50,000 belonged to the Regional and Popular Forces. Those forces were equipped with 449 tanks and armoured vehicles, 418 artillery pieces, 64 M-42 Duster light air-defence weapons, 373 aircraft of different types, and 165 naval vessels of different sizes.

Defensive strategy
In combination with the ‘Ly Thuong Kiet Military Plan’ and experiences gained during the North Vietnamese Nguyễn Huệ Offensive, Lieutenant General Ngo Quang Truong organised the defences of I Corps into three phases, to be staged from three different areas.

Defensive Phases
The first phase, known as the ‘orange phase’, was considered to be the most important because it provided South Vietnamese units in I Corps with a platform to stop enemy attacks, and even attack them if necessary. To accomplish the objectives of the ‘orange phase’, General Truong placed several elite combat units such as the Ranger groups and armoured forces on constant combat alert. The second phase, known as the ‘green phase’, was designed to delay enemy forces and buy more time for the South Vietnamese to regroup in order to stage a counter-attack, in the scenario that enemy forces managed to overcome the ‘orange phase’. In the final phase, or the ‘blue phases’, require South Vietnamese units to secure their areas of defence, then destroy and push enemy forces out of I Corps.

Areas of Defence
General Truong's areas of defence were centred on Tri Thien-Huế, Da Nang, and Quảng Nam-Quảng Ngãi.

Tri Thien-Huế

 * The task of holding Tri Thien and Huế was entrusted to the ARVN 1st Infantry Division, the 4th and 15th Ranger Groups, the 913th and 914th Regional Forces Companies, the 17th and 20th Armoured Squadrons, 10 artillery battalions, one squadron of helicopters, two squadrons of reconnaissance aircraft, and one coastal patrol squadron. Those forces were commanded by Lieutenant-General Lam Quang Thi.

Da Nang

 * Da Nang was under the direct responsibility of Lieutenant-General Ngo Quang Truong. It was home of the ARVN 3rd Infantry Division, the 4th and 7th Armoured Squadrons, the 11th and 14th Ranger Groups, the 911th Regional Force Company, the 1st Air Force Division, one coastal patrol squadron and two riverine squadrons.

Quảng Nam-Quảng Ngãi

 * Quảng Nam and Quảng Ngãi was held by the ARVN 3rd Infantry Division, the 12th Ranger Group, the 11th Armoured Squadron, three artillery battalions, the 912th Regional Force Company, one coastal patrol squadron and one riverine squadron. Brigadier-General Tran Van Nhut commanded the 3rd Infantry Division, and all other units in Quảng Nam and Quảng Ngãi.

Prelude
On March 5, 1975, the North Vietnamese 2nd Army Corps officially commenced its campaign against South Vietnamese forces of I Corps. The opening shots of the campaign was marked by an attack on South Vietnamese military convoys on Mount Hai Van, and the destruction of An Lo Bridge on National Highway 1, located north of Huế. Positions held by the ARVN 913th Regional Force at Dong Ong Do and Hill-368 also came under attack, as Phu Bai Airbase was subjected to intense artillery bombardment. While the South Vietnamese were busy dealing with those attacks, General Nguyen Huu An secretly redeployed the 325th Division and the 9th Regiment of the 304th Division, from Quảng Trị towards Huế in the south. The 46th and 271st Regiment then moved into positions previously held by the 325th Division and 9th Regiment. And, to fool South Vietnamese intelligence agencies, the North Vietnamese also moved tank and artillery units to Cua Viet, Thanh Hoi and Ai Tu to cover their main thrust.

Between March 6 and 7, the Viet Cong 4th Local Force Battalion assaulted and overran Mai Linh and 11 other surrounding military sub-sectors in Quảng Trị Province. On the following day, General Lam Quang Thi requested reinforcements from General Ngo Quang Truong in Da Nang, as a response to Communist attacks in his area of control. Meanwhile, the North Vietnamese 2nd Army Corps continued their onslaught, with the 324th Division launching attacks on South Vietnamese positions in Mo Tau, and on Hill-75, Hill-76, Hill-224, Hill-273, and Hill-303 all located south of Huế. By March 10, several South Vietnamese units were defeated in their attempts to hold off the North Vietnamese; the 1st and 54th Infantry Regiments, ARVN 1st Infantry Division, was destroyed on Hill-224 and 273; the ARVN 47th Armoured Squadron was overran by the VPA 1st Regiment, 324th Division, on Mount Nghe; and the ARVN 113th Regional Force Battalion conceded Pho Lai to the VPA 4th Regiment, which was supported by the 223rd Artillery Regiment. General Thi then ordered the 15th Ranger Group and the 2nd Battalion of the 54th Infantry Regiment, with support from the 27th and 37th Tank Squadrons, to mount a counter-attack on Hill-224. Over the period of one week, both sides fired over 8,000 rounds of artillery shells on Hill-224, and the South Vietnamese air force conducted over 60 bombing sorties in an attempt to halt the advances of the North Vietnamese 2nd Army Corps.

On March 13, amidst heavy fighting in the northern provinces of South Vietnam, General Ngo Quang Truong flew out to Saigon for a meeting with President Nguyễn Văn Thiệu. In this meeting, President Thieu outlined his decision to abandon most of the provinces in I Corps Tactical Zone, and ordered General Truong to withdraw his forces towards the coastal regions of central Vietnam instead. In addition, the Airborne Division would be redeployed to the Mekong Delta region, where it could protect the nation's capital. Unwilling to concede the northern provinces to the enemy, General Truong tried unsuccessfully to convince President Thieu to reverse his decision in the believe that he could hold onto I Corps, and recapture lost territories by using the Airborne and Marine Corps Divisions. After he returned to his headquarters that afternoon, General Truong decided to redeploy his forces instead of carrying out President Thieu's order straightaway, for several reasons. Firstly, he wanted to convince the President that most South Vietnamese units were still intact, and that they still had the time to recapture lost territories. And secondly, General Truong did not want to create confusion amongst his subordinates, when the military situation in I Corps was still under control.

Thus, General Truong reorganised his defences in order to deal with the threat posed by North Vietnamese formations located south of I Corps; he designated Da Nang to be the main centre of South Vietnamese defence in I Corps, with Tri Thien in the north, and with Quảng Nam and Quảng Ngãi in the south. To make up for the loss of the Airborne Division, General Truong ordered the 369th Marines Brigade to replace the 3rd Airborne Brigade in Quảng Nam Province, and the 258th Marines Brigade to take over from the 2nd Airborne Brigade on Mount Phu Gia, located north of Hai Van. Meanwhile, between March 13 and 15, the VPA 6th Regiment launched several attacks on Chuc Meo, La Son, Hill-300 and Hill-511 located west of Huế, forcing elements of the ARVN 1st Infantry Division to pull back towards Dong Tranh and Binh Dien. On March 17, the North Vietnamese High Command predicted that South Vietnamese units could withdraw into the cities of Huế and Da Nang, so the following orders were issued to North Vietnamese field commanders: General Le Tu Dong's forces were to capture Phu Bai Air Base to prevent aerial transportation, and cut off a section of Highway 1 north of Huế, and General Nguyen Huu An's 2nd Army Corps must secure Highway 1 south of the city, with the aim of isolating both Huế and Da Nang from the rest of the country.

On the following day, General Dong's forces staged their attacks from two main directions, from Thanh Hoi and Tich Tuong-Nhu Le, moving along Route 68 and National Highway 1 respectively. The North Vietnamese 2nd Army Corps, on the other hand, assaulted South Vietnamese positions in Phu Loc and Phu Gia. By 8:30pm on the evening of March 18, most of northern Quảng Trị was under North Vietnamese control. ARVN Colonel Do Ky, also the provincial chief of Quảng Trị Province, tried to lead what is left of his troops back to Huế but was pursued by the North Vietnamese along National Highway 1 until they reached An Lo. As the fighting in Quảng Trị unfolded, General Ngo Quang Truong flew back from Saigon where he tried to obtain approval from President Nguyễn Văn Thiệu for his new defensive plan, and hastily reorganised South Vietnamese defences in the northern regions of I Corps. Subsequently, General Truong sent out the following orders: the 480th Marines Brigade to leave Da Nang and to guard the north-western flank of Huế; the 1st Infantry Division, the 15th Ranger Group and the 7th Tank Squadron to protect south-western Huế; and the 258th Marines Brigade and the 914th Regional Force Battalion were to secure a section of Highway 1 which connected Huế with Da Nang.

Fall of Huế
While General Ngo Quang Truong was still busy reorganising South Vietnamese units in I Corps, on March 20 the Tri Thien Command finalised their plan to capture Huế, with the objective of preventing South Vietnamese forces from regrouping there. At 2:30pm on the same day, President Nguyễn Văn Thiệu phoned the ARVN 1st Brigade Headquarters, and ordered General Truong to defend only Da Nang due to the lack of resources. Beginning at 5:40am on March 21, the VPA 325th and 324th Divisions attacked South Vietnamese units positioned astride Highway 1. At the same time, elements of the K5 Special Forces Battalion destroyed Thua Luu Bridge, which connected a stretch of road on Highway 1 between Huế and Da Nang, forcing thousands of South Vietnamese civilian and military vehicles heading towards Da Nang to turn back. The ARVN 20th Tank Squadron was then sent out to reopen Highway 1, but was defeated by the VPA 203rd Armoured Regiment.

In light of the worsening military situation on the evening of March 22, General Ngo Quang Truong authorised General Lam Quang Thi to pull his forces back to Da Nang. However, as the main roads were blocked by the North Vietnamese, General Thi's only option was to use a coastal corridor between Thuan An and Tu Hien, and board transport vessels belonging to the 106th Navy Squadron and head back to Da Nang. On the morning of March 23, the VPA 324th Division advanced through Hill-303 and Mo Tau, and assaulted northern Phu Loc, while the VPA 325th Division captured Mui Ne, Phuoc Tuong, and encircled Tu Hien located south of Huế. In the north, the Viet Cong 4th, 46th and 271st Regiments pursued a retreating South Vietnamese formation consisted of the 147th Marines Brigade, the 14th Ranger Group, 5th Infantry Regiment (part of the 1st Infantry Division), and the 17th Armoured Squadron, heading towards Thuan An. And, at 4.30pm on March 23, the VPA 101st Regiment (part of the 325th Division) overran Luong Dien, and surrounded Phu Bai Air Base, to open the main corridor leading into Huế from the south. Simultaneously, the Viet Cong 46th Regiment destroyed South Vietnamese defences on Bo River, captured the districts of Quang Dien, Quang Loi and Huong Can, and secured the main roads on the outskirts of northern Huế.

Between March 24 and 25, the VPA 3rd (324th Division) and 101st Regiments continued their drive towards Huế, after they successfully captured Phu Bai Air Base. At the same time, the 1st Regiment (324th Division) along with the Viet Cong 4th and 271st Regiments were able to destroy the last elements of the ARVN 147th Marines Brigade and the 15th Ranger Group, before they could board navy vessels anchored off the shores of Huong Thuy, Luong Thien and Ke Sung and Cu Lai. By the evening of March 25, the North Vietnamese had secured all major points surrounding Huế, and South Vietnamese units that failed to escape were completely surrounded. Consequently, the North Vietnamese claimed to have captured large numbers of South Vietnamese prisoners and military hardware. In all, a total of 58,722 South Vietnamese soldiers became prisoners of war, with one colonel and 18 lieutenant-colonels amongst the ranks, as well as about 14,000 South Vietnamese government officials and employees, who reported to the North Vietnamese military authorities. The South Vietnamese military in Huế also surrendered vast quantities of weaponry, which included 140 tanks and armoured vehicles.

Nam-Ngai Campaign
From the beginning of March 1975, the combined North Vietnamese and Viet Cong forces of Military Region 5 had been coordinating their efforts with the 2nd Army Corp and Tri Thien Command to isolate General Ngo Quang Truong's I Corps from II Corps, led by Major-General Pham Van Phu. North Vietnamese and Viet Cong areas of operations in the southern regions of I Corps mainly centred in south-western Quảng Nam and north-western Quảng Ngãi, which included Tien Phuoc, Tam Ky, Nui Thanh, Tra Bong and Binh Son. Regular units of the Vietnam People's Army such as the 2nd Division, the 141st Regiment (3rd ‘Gold Star’ Division), the 52nd Independent Brigade, the 368th and 572nd Artillery Regiments operated alongside local Viet Cong units, namely the 94th and 96th Local Force Regiments, and 70th and 72nd Local Force Battalions. The southern region of I Corps was considered to be the weakest area of defence, which was under the responsibility of ARVN General Tran Van Nhut, who also led the 2nd Infantry Division. Also included in General Nhut's order of battle were the 12th Ranger Group, the 916th Regional Force Battalion, the 11th Armoured Brigade, three battalions of artillery, one navy coastal squadron and riverine squadron.

Beginning at 4:30am on March 10, North Vietnamese and Viet Cong forces proceeded to capture the following targets: the VPA 38th Regiment overran the highpoints of Nui Vu, Nui Ngoc, Duong Con, Soui Da and Nui Vy; the 36th Regiment destroyed South Vietnamese strong points at Trung Lien, Mount Da, Mount Khong ten, Ho Bach and Hill-215; the Viet Cong ‘Ba Gia’ Regiment held their positions on Hill-269 and Hill-310, to stop South Vietnamese counter-attacks from Tuan Duong; while the 52nd Independent Brigade captured Go Han, Phuoc Tien, Duong Ong Luu, Duong Huế, Nui My, Hon Nhon, Deo Lieu, and Mount Đất Đỏ. Thus, 23 positions held by units of the ARVN 12th Ranger Groups were captured, just after four hours of fighting. At 9:00am on March 10, North Vietnamese soldiers of the 368th Artillery Regiment dragged 12 pieces of artillery which included 85mm, 105mm and 122mm guns onto the top of Nui Vu and Han Thon, and aimed their guns directly on Hill-211 and the administrative centre of Tien Phuoc, to support the 31st Regiment attacking those areas. At 1:30pm, following two failed counter-attacks, South Vietnamese units in Phuoc Lam deserted from the battlefield. In the mean time, however, South Vietnamese troops in Tien Phuoc could bare held their ground with support from two A-37 bombers, after South Vietnamese commanders on the ground had called for reinforcement from Chu Lai. By 4:00pm, Tien Phuoc was captured by the VPA 2nd Division.

Due to the lost of Tien Phuoc and Phouc Lam, the ARVN 916th Regional Force Battalion retreated from the area. Thus, Tam Ky, the capital of Quảng Nam Province, was threatened to be overrun by the North Vietnamese. On March 11, General Ngo Quang Trong ordered General Tran Van Nhut to mobilise the 2nd Infantry Division, the 12th Ranger Group, elements of the 11th Armoured Squadron and one regional force battalion to mount a counter-attack from Tuan Duong to Cam Khe and Duong Con. General Truong also ordered the ARVN 2nd Infantry Regiment (3rd Infantry Division) to depart from Da Nang, and protect Tam Ky, so that General Nhut's forces could be free up to fight the North Vietnamese. However, between March 14 and 15, the ARVN 2nd Infantry Regiment was forced to turn back from Tam Ky to deal with an attack on Thang Binh, by the Viet Cong 70th and 72nd Local Force Battalions. In southern Quảng Ngãi, the Viet Cong 94th Local Force Regiment attacked Binh Son, cut off a section of National Highway 1 near Chau O, and the ARVN 4th Infantry Regiment (2nd Infantry Division) was pinned down trying to deal with Viet Cong attacks. Thus, South Vietnamese attempts to stage an effective counter-attack were quickly blunted by the combined Viet Cong and North Vietnamese forces in Quảng Ngãi Province. Recognising that he no longer has the manpower to mount a counter-attack, General Nhut ordered his troops to abandon Tra Bong and Son Ha, and concentrate his units in Tam Ky and Chu Lai instead.

Following the failed counter-attack, South Vietnamese forces in I Corps was further weakened when President Nguyễn Văn Thiệu pulled the Airborne Division back to Saigon. Now that the South Vietnamese 2nd Infantry Division and the 12th Ranger Group was overstretched between Quảng Ngãi and Hội An, with Tam Ky only defended by the ARVN 5th Infantry Regiment and one battalion from the ARVN 4th Infantry Regiment, North Vietnamese General Chu Huy Man decided to utilise the advantage to capture Tam Ky. Beginning at 5:30am on March 21, the North Vietnamese 2nd Division attacked Suoi Da, the last South Vietnamese outpost outside Tam Ky. At around 12:00pm, ARVN General Tran Van Nhut ordered the rest of the 4th Infantry Regiment out from Quảng Ngãi in an attempt to hold Tam Ky, so South Vietnamese defences in that province was further weakened. Again, taking advantage of the situation, General Chu Huy Man ordered the 52nd Independent Brigade and the 94th Local Force Regiment to attack Quảng Ngãi. By 7:00am on March 24, the cities of Tam Ky and Quảng Ngãi were simultaneously attacked by North Vietnamese and Viet Cong forces. In Tam Ky, the ARVN 4th and 5th Infantry Regiments were destroyed after two hours of heavy fighting, while the 37th and 39th Ranger Battalions (from the ARVN 12th Ranger Group) in the outskirts of the city simply fled from the battlefield. At 10:00am on March 24, North Vietnamese and Viet Cong soldiers of the 2nd Division, the ‘Ba Gia’ Regiment, and the 31st Regiment successfully captured Tam Ky.

In Quảng Ngãi, the VPA 52nd Independent Brigade, with support from two special forces battalions, as well as tanks and armoured vehicles from the 574th Regiment, rolled over South Vietnamese defences. At around 2:00pm, the surviving elements of the ARVN 6th Infantry Regiment, the rest of the 12th Ranger Group and the 4th Tank Squadron was ambushed by the Viet Cong 94th Local Force Regiment along National Highway 1, when they tried to retreat towards Chu Lai without a fight. As a result, over 600 South Vietnamese soldiers were killed, and around 3,500 others were captured. At 11:30pm on March 24, the North Vietnamese was in full control of Quảng Ngãi City. On March 25, 1975, the Nam-Ngai Campaign concluded with North Vietnamese and Viet Cong forces exercising full control over the provinces of Quảng Nam and Quảng Ngãi, leaving Da Nang as the only major city in I Corps still held by the South Vietnamese. As such, out of the 44 provinces in South Vietnam, 10 were occupied by the Vietnam People's Army, while three ARVN infantry divisions were rendered ineffective. In addition, the elite ARVN 147th Marines Brigade ceased to exist as a fighting force.

South Vietnamese dispositions
By 1975, Da Nang had been become the second largest city in South Vietnam, with close to a million inhabitants. It was a major economic and political centre in I Corps Tactical Zone, and was home to the largest military installations which incorporated the South Vietnamese army, navy and air force. Logistically, the military infrastructure within the city could hold several thousand tons of weaponry, ammunition, food supplies and other essential war materials. It also had four large seaports, and a major airport at Da Nang and Nuoc Man. So, on March 25, following the loss of Quảng Trị, Thừa Thiên, Quảng Nam and Quảng Ngãi, President Nguyễn Văn Thiệu ordered South Vietnamese commanders at all levels to hold what was left of I Corps till the very end. On March 26, General Ngo Quang Truong gathered what was left of his units, about 75,000 soldiers, and organised them into the following order:


 * Outer Defensive Line: The 258th Marines Brigade and the 914th Regional Force Battalion to hold all areas between Phuoc Tuong and Lien Chieu. The 369th Marines Brigade and the 57th Infantry Regiment (3rd Infantry Division) were to protect Dai Loc and Dong Lam. The surviving elements of the 147th Marines Brigade, and the Marine Corps Division Headquarters would hold Nuoc Man airfield. Meanwhile, the remnants of the 3rd Infantry Division would hold Vinh Dien and Ninh Que, while the 15th Ranger Group held Ba Ren.


 * Inner Defensive Line: The 912th Regional Force Battalion, and the last elements of the 11th and 20th Armoured Squadrons held Phuoc Tuong-Hoa My. The last three battalions of the 1st Infantry Division, the 2nd Infantry Division, the 12th Ranger Group, and about 3,000 freshly trained soldiers from the Hoa Cam Training Camp were ordered to defend all key areas between Hoa Cam and Nuoc Man. All independent Regional and Popular Force battalions were placed in reserve, and could go into combat when required.

General Truong also had 12 artillery battalions at his disposal, as well as the 1st Air Force Division based at Da Nang and Nuoc Man, which were still intact despite the early clashes in I Corps.

North Vietnamese plan of attack
Following the conclusion of the Tri Thien and Nam-Ngai Campaigns, the Vietnam People's Army High Command ordered General Le Trong Tan to journey south from Hanoi and personally take charge of the Da Nang Campaign. Subsequently, on March 25, the North Vietnamese came up with a plan to attack Da Nang from four directions:


 * North: The 325th Division (without the 95th Regiment), with support from one tank battalion and one artillery battalion, were ordered to advance along National Highway 1 and capture the ARVN 1st Brigade Headquarters, the South Vietnamese 1st Air Force Division at Da Nang, and then move on to the Son Tra Peninsula to capture the main seaport there.


 * North-West: The 9th Regiment (304th Division), with support from one tank battalion, one artillery battalion and one anti-aircraft gun battalion, were ordered to advance along Highway 14B, and capture the ARVN 3rd Infantry Division Headquarters at Phuoc Tuong, and then move on to Da Nang Air Base.


 * South & South-East: The 2nd Division, with support from one artillery unit (the 36th Artillery Regiment), one artillery battalion, one tank-armoured vehicles battalion, one anti-aircraft gun battalion, and one anti-tank weapons company, were ordered to take Da Nang Air Base and the ARVN 1st Brigade Headquarters, then capture the city itself. The 3rd and 68th Regiments were placed in reserve.


 * South-West: The 2nd Army Corps (without the 9th Regiment, 304th Division) was ordered to take all positions held by the ARVN 369th Marines Brigade along the defensive line at Thuong Duc-Ai Nghia-Hiep Duc, then advance toward Nuoc Man airfield. The 24th Regiment (304th Division) was required to capture Hoa Cam, and then move on to Da Nang.

The fight begins
Before the North Vietnamese finalised their plan to capture Da Nang, the 2nd Army Corps had already begun making preparations for the final attack on the city. On March 24, the VPA 325th Division fought with the ARVN 258th Marines Brigade and the 914th Regional Force Battalion at North Hai Van, and overran Phuoc Tuong, Nuoc Ngot, Tho Son and Thua Luu. Consequently, North Vietnamese forces captured enemy artillery positions in Phuoc Tuong, and made good use of it during the following weeks. On March 27, with air-support from A-37 attack aircraft from Da Nang, the 258th Marines Brigade and the 914th Regional Force Battalion tried to hold off North Vietnamese forces at Phu Gia and Hai Van, but they were pushed back and sustained heavy casualties in the process. The VPA 325th Division then continued their advance through So Hai, Loan Ly, An Bao and Lang Co. Soon afterwards, more than 30 artillery pieces belonging to the VPA 84th and 164th Artillery Regiments were placed at various high points in Son Thach, Son Khanh and Mui Trau; beginning at 5:30am on March 28, North Vietnamese artillery units bombarded South Vietnamese positions around Da Nang. Meanwhile, the ARVN 369th Marines Brigade quickly abandoned their position at Son Ga, after they had detected elements of the VPA 304th Division conducting reconnaissance missions on the battlefield. On March 28, the VPA 66th Regiment (304th Division) attacked and captured the administrative area of Ai Nghia and Nuoc Man airfield, while the VPA 24th Regiment attacked Hoa Cam and Toa in the outskirts of Da Nang.

The ARVN 369th Marines Brigade then tried to pull back towards An Dong and My Khe, but they were pursued by the VPA 2nd Division. Meanwhile, the 3,000 South Vietnamese soldiers at Hoa Cam mutinied against their commanding officers, and surrendered to the North Vietnamese. South of Da Nang, the VPA 2nd Division, with support from tank and artillery units was able to overrun Ba Ren at around 9:00am on March 28. In response, ARVN General Ngo Quang Truong ordered Air Force Brigadier-General Nguyen Van Khanh to send a squadron of four A-37 bombers to destroy the main bridges at Ba Ren and Cau Lau, but they could not prevent the VPA 2nd Division from crossing the river using canoes, and other small river crafts. At 5:55am on March 29, the outer South Vietnamese defence line located south of Da Nang succumbed to the North Vietnamese. At 6.30am on the same day, the last South Vietnamese strongholds in and around Hai Van were overrun by the North Vietnamese. The VPA 325th Division then secured Lien Chieu, the Nam O Bridge and the Trinh Me The Bridge, thereby clearing the main road for the supporting tank and armoured units to advance on Son Tra. As North Vietnamese troops were closing in, General Ngo Quang Truong and other high-ranking South Vietnamese officers were airlifted out to the coastal areas, where they boarded the navy transport ship HQ-404. At 12:00pm, the ARVN 1st Brigade Headquarters was finally captured. At 12:30pm, the 9th Regiment (304th Division) also captured the ARVN 3rd Infantry Division Headquarters, and quickly established their control over the entire Phuoc Tuong area.

By the time Da Nang fall into North Vietnamese hands, South Vietnamese commanders on the ground simply lost control of their men as military discipline collapsed. On March 28, about 6,000 South Vietnamese soldiers of the 2nd Infantry Division deserted, and left the battlefield. And then the soldiers of the ARVN 3rd Infantry Division also retreated, thereby leaving the rear of the Marine Corps Division exposed to enemy attacks. Since March 25, from the CIA Station in Da Nang, Al Francis and the U.S. Embassy in Saigon began formulating an evacuation plan, in order to evacuate U.S. citizens and South Vietnamese government officials out from Da Nang. As part of the plan, aircraft belonging to civilian airliners were to be used. And in addition to the South Vietnamese navy vessels of I Corps, U.S. General Homer Smith also provided five barges, six passenger liners, and three cargo ships to help with the evacuation process. Even though the evacuation plan was designed to be carried out in an orderly manner, chaos and confusion quickly descended on the civilian and military population of Da Nang as people fought each other to board the vessels anchored off the coast. On the afternoon of March 29, North Vietnamese soldiers of the 2nd, 304th, 324th and 325th Divisions, as well as the 203rd Armoured Regiment, entered the city of Da Nang.

Casualties
The struggle for Huế and Da Nang had cost South Vietnam its entire army corps, namely the units of the ARVN 1st Brigade, I Corps Tactical Zone. According to the Socialist Republic of Vietnam's official history, apart from the 16,000 soldiers and civilians who managed to escape, over 120,000 South Vietnamese soldiers were killed, wounded or captured after the fall of Huế and Da Nang. In their attempt to abandon the territories of I Corps, the South Vietnamese military left behind vast quantities of U.S.-supplied military hardware. The North Vietnamese claimed to have captured 129 aircraft of different models, 179 tanks and armoured vehicles, 327 artillery pieces, 184 transport vehicles and 47 naval crafts. More than 10,000 tons of bombs, ammunition, grenades, food supplies, combat rations, and other materials were also captured. Total North Vietnamese and Viet Cong casualties are largely unknown.

South Vietnam and the loss of the northern provinces
President Nguyễn Văn Thiệu's decision to abandon the Central Highlands and the coastal regions of I Corps had a negative impact on the fighting ability of South Vietnamese troops, especially as the northern provinces of South Vietnam were driven into chaos. On March 31, after the fall of Huế and Da Nang, ARVN General Pham Van Phu-commander of II Corps Tactical Zone- held a meeting with his General Staff and the provincial chiefs of Bình Định, Khánh Hòa, Phú Yên, Ninh Thuận and Bình Thuận, and requested them to form a defensive line from Qui Nhơn into the Mekong Delta to cover the retreat of the ARVN 2nd Brigade from the Central Highlands. Subsequently, General Phu issued the following orders: Rear Admiral Hoang Co Minh was to oversee military operations in the Qui Nhơn region, Brigadier-General Tran Van Cam to hold Phú Yên, Brigadier-General Nguyen Ngoc Oanh and Brigadier-General Nguyen Van Luong was tasked with holding Nha Trang. Meanwhile, General Phan Dinh Niem- commander of the ARVN 22nd Infantry Division- was required to form a defensive line linking Qui Nhơn with Diêu Trì and Deo Ca, with the purpose of delaying North Vietnamese forces.

The withdrawal plan formulated by General Pham Van Phu and his General Staff was made with the believe that North Vietnamese and Viet Cong forces would stop and consolidate their territorial gains, before they could go on the attack again. However, during the spring offensive of 1975, North Vietnamese commanders were more than willing to manoeuvre their units away from newly captured territories, in order to pursue retreating South Vietnamese units. Furthermore, South Vietnamese commanders never realised that Hanoi had given its field commanders the full flexibility to respond to the changing circumstances on the battlefield, and had supplied North Vietnamese units with weaponry required to achieve their objectives. Ultimately, the average South Vietnamese soldiers would have to pay for the miscalculation of their commanders. At 5:15am on March 31, the 47th Infantry Regiment (ARVN 22nd Infantry Division) was ambushed by the 2nd Regiment (VPA 3rd ‘Gold Star’ Division), while withdrawing towards Phu An-Lai Nghi. Upon arrival at Phu Cat, the remnants of the ARVN 47th Infantry Regiment was encircled and assaulted by the VPA 198th Regiment, and ceased to exist as a fighting unit by 12:30pm.

The 41st Infantry Regiment (ARVN 22nd Infantry Division) also came under attack from the VPA 95th Regiment, as they moved from Nui Mot to Phu Phong. Throughout the evening of March 31, the ARVN 41st Infantry Regiment fought with the VPA 141st Regiment, as soon as they reached Phat Giao. In contrast to the other units, the 42nd Infantry Regiment (ARVN 22nd Infantry Division) was able to escape the North Vietnamese onslaught, but their strength was significantly reduced before they reached Dieu Tri. On April 1, Quy Nhon fall into the hands of the North Vietnamese, which was followed by Tuy Hòa on April 2. ARVN General Tran Van Cam was captured in Tuy Hòa after his helicopter had landed on the ground, where he tried to survey the battlefield. The destruction of the ARVN 22nd Infantry Division, which had about 10,000 fully equipped men, stirred up chaos in Nha Trang; more than 3,000 South Vietnamese recruits from the Lam Son Army Training Centre retreated into the city, while another 1,000 soldiers went on a rampage and looted goods on the main streets. The chief of Khánh Hòa Province, Colonel Ly Ba Pham, boarded a military aircraft and flew out to Phan Rang, after he had notified Saigon that "the situation is irreversible". On the afternoon of April 2, Nha Trang was overrun by the North Vietnamese, and not a single battle was fought in its defence. By 2:00pm on April 2, ARVN General Pham Van Phu had lost every military unit and territory under his control.

The decisions of President Nguyễn Văn Thiệu
According to many academics, both in Vietnam and in the West, the major factor which contributed to the rapid collapse of South Vietnamese defences in 1975 was the numerous, and contradictory orders issued by President Nguyễn Văn Thiệu. During the various phases of the South Vietnamese retreat from the northern provinces, namely in I and II Corps Tactical Zones, President Thieu had at least three different plans and decisions laid out before him, and each one either lacked consistency or simply contradicted one another. For example, on March 13, President Thieu ordered General Ngo Quang Truong to abandon I Corps, and return the elite Airborne Division to the Mekong Delta region of III Corps. Soon afterwards, similar orders were issued to Major-General Pham Van Phu to evacuate from the Central Highlands. Then, on March 17, with intervention from General Cao Van Vien, President Thieu contradicted his previous orders when he approved General Truong's defensive plan to hold the major cities of Huế and Da Nang.

However, the very next day, President Thieu ordered General Ngo Quang Truong and General Lam Quang Thi to abandon Huế, and only concentrate sufficient numbers of South Vietnamese units to hold Da Nang. On March 29, as General Truong was about to board the navy transport ship HQ-404, he received a phone call from President Thieu, who ordered him to turn back and retake Da Nang from the North Vietnamese forces. By that stage, however, South Vietnamese units in I Corps had virtually disappeared, while their commanding officers had fled from their posts. So General Truong refused to carry out President Thieu's orders. Between April 3 and 4, President Thieu reprimanded General Pham Van Phu and General Lam Quang Thi for the debacles in II and I Corps respectively, and Generals Pham Quoc Thuan and Du Quoc Dong for the fall of Phước Long in 1974. Even though President Thieu used the defeat of South Vietnamese forces as a justification for the arrest of those generals, his real intention behind the arrests was to avert an imaginary military coup against him. For that reason, he chose to pull the Airborne Division back to III Corps, which was commanded by loyalist officers, instead of the Marine Corps Division.

General Ngo Quang Truong and General Le Nguyen Khang were spared, but both men responded strongly to President Thieu's reaction. In General Truong's view, the aforementioned generals were victims of injustice, as they were far more competent than Thieu's loyalists in Saigon. In addition to the military disasters suffered on the battlefield, President Nguyễn Văn Thiệu also caused instability within his own government during the final days of South Vietnam's existence. For example, on April 2, President Thieu requested the country's National Assembly to dissolve Prime Minister Tran Thien Khiem's cabinet, and replace him with Nguyen Ba Can. The National Assembly quickly approved President Thieu's request. Then on the same day, President Thieu also ordered the arrest of seven individuals who had worked for Air-Marshal Nguyen Cao Ky, believing they were plotting to overthrow him. William Colby—CIA Chief of Station in Saigon—wrote in a report back to Washington that the balance of power had leaned in Hanoi's favour. As such, if South Vietnam were to survive the North Vietnamese onslaught, whoever replaced President Thieu would have to accept a resolution to the conflict on North Vietnamese terms.