The bombing of Kure and surrounding areas by United States and British naval aircraft in late July 1945 led to the sinking of most of the surviving large warships of the Imperial Japanese Navy (IJN). The United States Third Fleet's attacks on Kure Naval Arsenal and nearby ports on 24, 25, and 28 July sank an aircraft carrier, three battleships, five cruisers, and several smaller warships. During the same period the British Pacific Fleet attacked other targets in the Inland Sea region and sank two escort ships and several smaller vessels as well as damaging an escort carrier.
In July 1945 the IJN's remaining large warships were concentrated near the major naval base of Kure. The ships were effectively immobilized due to fuel shortages and were being used only as stationary anti-aircraft batteries. Admiral John S. McCain, Sr., the commander of the Fast Carrier Task Force, strongly opposed attacking Kure as he and his staff believed that the ships only posed a minor threat.
In his memoirs Admiral Halsey gave four reasons for why he attacked Kure despite McCain's objections. Firstly, he believed that the attack would boost US morale and retaliate for the Attack on Pearl Harbor in December 1941, secondly it would ensure that the Japanese could not disrupt the planned Soviet invasion of Hokkaido, thirdly it would prevent Japan from using its fleet as a bargaining point to secure better peace terms and finally that he had been ordered to conduct the attack by his superior officer, Fleet Admiral Chester W. Nimitz.
Despite operating as a task group of the US Third Fleet, the British Pacific Fleet was excluded from the attack on Kure so that Britain would not be able to claim a part in destroying the Japanese fleet. The BPF was instead used to attack airfields and the port of Osaka.
Kure had been subjected to several major attacks by B-29 Superfortress bombers of the United States Army Air Forces in 1945, prior to the US Navy's attack in late July. The Hiro Naval Aircraft Factory was successfully bombed on 5 May, naval mines were laid in the approaches to the port on 30 March and 5 May and 40 percent of the city was destroyed in a major air raid on 1 July.
The Third Fleet's attack against Kure began on 24 July. US carrier aircraft flew 1,747 sorties on this day against Japanese targets. The attacks were successful, and resulted in the sinking of aircraft carrier Amagi, and the cruiser Ōyodo, which at this time was acting as the Combined Fleet's flagship. The battleships Hyūga, Ise, and Haruna, the heavy cruisers Tone and Aoba, and the old armored training cruisers Iwate and Izumo were all heavily damaged and settled in shallow water. The shallow anchorage precluded the use of torpedos. The US aircraft attempted to reduce their losses from the large number of anti-aircraft guns in the area by the use of variable time-fused bombs.
US strikes against Kure resumed on 28 July and resulted in the further damaging of the battleships Ise and Haruna, and the heavy cruiser Aoba. The aircraft carrier Katsuragi which had largely escaped attack in the earlier raid, and the unserviceable light aircraft carrier Ryūhō were attacked, with Katsuragi suffering heavy damage. These air strikes were among the largest conducted by the US Navy during the war, and were the most destructive of shipping.
The USAAF also launched an attack of the Japanese ships at Kure on 28 July. This raid was made up of 79 B-24 Liberators based on Okinawa. Four bomb hits were made upon the beached cruiser Aoba. The bomb strikes further damaged the vessel, and caused her stern to be broken off. The raid suffered the loss of two B-24s shot down and 14 others suffered damage.
Allied losses included 102 aircrew and 133 planes lost in combat or accidents during the attacks. These losses were higher than those suffered by the Third Fleet in most of its operations, and were the result of the heavy anti-aircraft defences around Kure.
The Allied attacks on Kure and the inland sea left the Nagato at Yokosuka as the only remaining capital ship in Japan's inventory. The destruction of her battleships and heavy cruisers at Kure was seen by British official historian Stephen Roskill as avenging the losses suffered by the United States at Pearl Harbor. The attacks allowed the Soviet Pacific Fleet to operate without fear of interdiction in the Sea of Japan.