Tunnel warfare

Tunnel warfare is a general name for the war being conducted in tunnels and other underground cavities.It often includes the construction of underground facilities in order to attack or defense, and the use of existing natural caves and artificial (catacombs, city communications, etc.)underground facilities for military purposes. Tunnels can be used to undermine fortifications and slip into territory, while it can strengthen a defense by creating the possibility of ambush, counterattack and the ability to transfer troops from one portion of the battleground to another unseen and protected. Also, tunnels can serve as the shelter of its troops and people from enemy attacks.

It can be sometimes linked with urban warfare, as tunnels are often found in urban areas and cities, although urban warfare as a whole usually dominates any tunnel considerations.

Tunnels, due to their nature, restrict fields of fire and thus any troops in a tunnel usually only have a few areas exposed to fire or sight at any one particular time. Also they can be part of an extensive labyrinth and have cul-de-sacs as well as reduced lighting that can create a closed-in night environment.

The origin of tunnel warfare in ancient warfare
Tunneling in order to mine enemy fortresses and make the walls crumble is an ancient military art that has been put in use all over the world. A famous mine made the walls of Kazan crumble, allowing the Russians to take it. The only countermeasure was to dig down, intercept the mine, and fight the advancing enemy soldiers underground. Sometimes the tunnels collapsed during the fighting, and both sides were buried alive.

The oldest known sources about employing tunnels and trenches for guerrilla-like warfare are Roman. After the uprising in Germania the insurgent tribes soon started to change defence from only local strongholds into utilising the advantage of wider terrain. Hidden trenches to assemble for surprise attacks were dug, connected via tunnels for secure fallback. In action often barriers were used to prevent the enemy from pursuing.

Roman legions entering the country soon learned to fear this warfare, as the ambushing of marching columns caused high casualties. Therefore they approached possibly fortified areas very carefully, giving time to evaluate, assemble troops and organize them. When the Romans were themselves on the defensive the large underground aqueduct system was utilised in the defence of Rome, as well as to evacuate fleeing leaders.

The use of tunnels as a means of guerrilla-like warfare against the Roman Empire was also a common practice of the Jewish rebels in Judea during the Bar Kokhba revolt (132–136 AD). With time the Romans understood that efforts should be made to expose these tunnels. Once an entrance was discovered fire was lit, either smoking out the rebels or suffocating them to death.

Medieval warfare
Tunneling was used throughout the world in the medieval period. Often they connected fortifications, towns, villages, religious and political buildings. They were used for supply, communication and as escape routes.

A particular use of tunneling was in mining, where tunnels, braced with timber supports, were dug under the fortifications of besieged castles or towns, which when fired would collapse, bringing down the overlying wall.

Modern warfare
Increased firepower that came with the use of gunpowder, cordite and dynamite made above ground fortifications very expensive if they should withstand any attack. Fortifications were covered with earth and finally they were built totally underground to protect crews and ammunition. For the purpose of firing, artillery and machine gun emplacements had loopholes.

Such a tunnel fortress was difficult to enter and inside there was no room for the attackers to hide from gunfire and explosives. On the other hand poison gas proved to have a devastating effect.

In trench warfare with heavily fortified strongholds, the tactic of digging and mining the enemy positions was used in the American Civil War during the Siege of Petersburg and the Russo-Japanese War during the Siege of Port Arthur. Extensive mining warfare was conducted by German, French, British and Australian troops on the Western Front during World War I, where the largely static frontlines created favourable conditions for mining.

The largest mining operations were conducted in the Battle of Messines, where specialist Royal Engineer tunnelling companies placed 22 mines under German lines. 19 were eventually exploded, killing about 10,000 German soldiers. Underground attacks especially broke the morale of the enemy if he was surprised in his secure positions. However, the huge craters that are the results of mining enemy positions could be obstacles during an advance, as was found at Petersburg Battle of the Crater and the Somme. Tunnels built to secure frontline supply were built in several places on the Western Front.

On the Eastern Front, the successful Brusilov Offensive employed tunnel/trenches to allow the Russian troops to start the initial assault very close to the Austrian trenches. During World War II, the rapid transit systems that existed in many cities became another military consideration.

The lessons of these battles led to the construction of even bigger systems of defence underground, like the Maginot line or the Westwall with their own infrastructures.

North Korea, it has been claimed, has prepared several transport tunnels with a capacity 10,000 troops per hour for a possible invasion of South Korea. This melds the defensive tunnel warfare with mobile warfare.

The term tunnel war or tunnel warfare (地道战) was first used for the guerrilla tactic employed by the Chinese in the Second Sino-Japanese War. The tunnel systems were fast and easy to construct and enabled a small force to successfully fight superior enemies.

Tunneling in the World War I
On the Western Front during the First World War, the military employed specialist miners to dig tunnels under No Man's Land. The main objective was to place mines beneath enemy defensive positions. When it was detonated, the explosion would destroy that section of the trench. The infantry would then advance towards the enemy front-line hoping to take advantage of the confusion that followed the explosion of an underground mine. It could take as long as a year to dig a tunnel and place a mine. As well as digging their own tunnels, the miners had to listen out for enemy tunnellers. On occasions miners accidentally dug into the opposing side's tunnel and an underground fight took place. When an enemy's tunnel was found it was usually destroyed by placing an explosive charge inside. At the beginning of the Somme offensive, the British denoted two mines that contained 24 tons of explosives. Another 91,111 lb. mine at Spanbroekmolen created a hole that afterwards measured 430 ft. from rim to rim. Now known as the Pool of Peace, it is large enough to house a 40 ft. deep lake. In January, 1917, General Sir Herbert Plumer, gave orders for 20 mines to be placed under German lines at Messines. Over the next five months more than 8,000 metres of tunnel were dug and 600 tons of explosive were placed in position. Simultaneous explosion of the mines took place at 3.10 on 7 June. The blast killed an estimated 10,000 soldiers and was so loud it was heard in London.

Sino-Japanese war in World War II
The Ranzhuang tunnel evolved in the course of fighting back Japanese's mopping-up for the people in the central area of Mainland China, Hebei province. During the Second Sino-Japanese war, the Chinese Communist forces or local peasant resistance used tunnel war tactics against the Japanese (and later Kuomingtang during Chinese Civil War). The tunnels were dug beneath the earth to cover the battlefield with numerous hidden gun holes to make a surprise attack. The holes and entrance usually were hidden beneath a straw mat inside a house, or down a well. This allowed flexible manoeuver or exit.

However, the main disadvantages of tunnel war is that usually the Japanese could fill up the holes or pour water in to suffocate the resistance fighter inside the tunnels. This proved to be a major problem but was later solved by installing filters that would consume the water and poisonous gases. It is said that there were even women and children who voluntarily fought in the tunnels.

This is a famous military facility in China due to the movie Tunnel War based on the stories happened during fighting Japanese in the tunnel. After the success of this war movie, more art pieces were produced and adapted in the same setting.

After the war, the Ranzhuang tunnel site ranked among key heritage preservation unit in China, Hebei province patriotism education base, national defense education base. Tens of thousands visitors were attracted each year. Most of the villagers were working in tourism service industry, an industry worth US$700,000 each year.

Japan-U.S. war in World War II
The first to copy tunnel warfare were the Japanese themselves. In the battles of the Western Pacific, they would maximize their capabilities by establishing a strong point defense, utilizing cave warfare. The first encounter of the US Marines with this new tactic was the island of Peleliu. The invading marines suffered twice as many casualties as on Tarawa, where the old Japanese tactic of defending the beach had been employed. The pinnacle of this form of defense, however, can be found on Iwo Jima, where the Japanese engineered the whole Mount Suribachi with many tunnels leading to defensive emplacements, or exits for quick counterattacks. Tunnel warfare by the Japanese forced the US Marines to adopt the "blowtorch and corkscrew" tactics to systematically flush out the Japanese defenders, one cave at a time.

Korean War
In the Korean War, the tactic of tunnel warfare was employed by the Chinese forces themselves. "The Chinese resort to tunnel warfare, and the devastating losses to American soldiers, led to the sealing of tunnel entrances by United Nations Command. According to later prisoner of war interrogations, Chinese officers had killed a number of their own soldiers in the tunnels, because the latter had wished to dig their way out and surrender to the United Nations Command."

Vietnam War
When Vietnam became a French colony again after the Second World War, the Communistic Vietminh started to dig tunnels close to Saigon. After the French army left (they were defeated at Dien Bien Phu) the tunnels were maintained in case the plausible war with South-Vietnam would start. Ho Chi Minh, leader of North-Vietnam, ordered to expand the tunnels after the Americans entered the war between the North and the South. The tunnels would be used by the Liberation Front for the Liberation of South-Vietnam (by the Americans shortened to Vietcom or VC, often pronounced as Vietcong). Systems of tunnels were not occupied temporarily for military purpose, but began to contain whole villages of people living permanently underground. The tunnels were a complete underworld, it was all there; kitchens, hospitals, workshops, sleeping areas, communications, ammunition storage, even some entertainment. The tunnels eventually became a target for American forces because the enemy could hide in it and strike everywhere in the range of the tunnel complex (hundreds of miles) without a single warning and then disappear again.

These tactics were also applied against the Chinese during the Sino-Vietnamese War.

Palestine-Israel war
Sometimes the ongoing conflict between Israeli Army and Palestinians under the border of Gaza is called tunnel war. The Palestinians have used tunnels in three ways: 1) Tunnels have been dug from the area of the town of Rafiah in the Gaza Strip into the area of Rafiah in Egypt. These tunnels are used to smuggle a wide variety of material into the Gaza Strip - some for civilian use (food, fuel etc.) but also a large amount of military supplies - weapons, ammunition and other military equipment. 2) Tunnels have been dug under Israeli army positions, filled with explosives and exploded. 3) A small number of tunnels were dug under the Gaza - Israel border on order to infiltrate into Israel. In one such incident in 2006 a tunnel was dug to a hidden position behind an Israeli tank position. At night a Palestinian team came out of the tunnel and fired an anti-tank rocket at the tank, then charged it. The crew was taken by surprise, three Israelis were killed and one was captured and abducted through the tunnel back into Gaza. The smuggling tunnels are by far the most numerous type because they are economically lucrative for the diggers, who earn a commission both for the digging and for the materials that pass through their tunnel. The Israelis conduct routine counter-tunnel operations in which over the past ten years they have discovered and destroyed hundreds of tunnels of all types.

Lebanon-Israeli War
In July 2006, a group of Hezbollah fighters crossed from southern Lebanon into northern Israel killing three Israeli soldiers and abducting two, which started the Lebanon-Israeli war. Faced with Israeli's air attacks, Hezbollah needed to create a defensive system that would enable these rocket attacks to continue uninterrupted throughout any conflict with Israel.To do so they created an intricate system of tunnels and underground bunkers, anti-tank units, and explosive-ridden areas. The tunnel network infrastructure includes a 25-km long tunnel, which is said to have received help from North Korea.

Sarajevo tunnel
Between between May 1992 and November 1995, during the Siege of Sarajevo and in the midst of the Bosnian War the Sarajevo Tunnel was constructed by the Bosnian Army in order to link the city of Sarajevo, which was entirely cut-off by Serbian forces, with the Bosnian-held territory on the other side of the Sarajevo Airport, an area controlled by the United Nations. The tunnel linked the Sarajevo neighbourhoods of Dobrinja and Butmir, allowing food, war supplies, and humanitarian aid to come into the city, and people to get out. The tunnel was one of the major ways of bypassing the international arms embargo and providing the city defenders with weaponry.

Famous tunnel war victories

 * Jiaozhuanghu (焦庄户) tunnel war in Ranzhuang, Hebei province that defeated the Japanese Army (later made into the movie Didao Zhan by the PRC)
 * Củ Chi tunnels a complex of over 200 km of tunnel systems that allowed NLF guerrillas during the Vietnam War to keep a large presence relatively close to Saigon.

Tunnels after war
Many of the famous war tunnels were later turned into tourist site due to their historic significance in wars.For example, Sarajevo tunnel is now converted into a war museum, with 20 meters of the original tunnel open for tourists visit. HebeiRanzhuang tunnel is also a famous war tourism site in China.