The bombing of Chongqing (, ), from 18 February 1938 to 23 August 1943, were massive terror bombing operations authorized by the Empire of Japan's Imperial General Headquarters and conducted by the Imperial Japanese Army Air Service (IJAAF) and Imperial Japanese Navy Air Service (IJNAF). Resistance was put up by the Chinese Air Force and the National Revolutionary Army's anti-aircraft artillery units in defense of the provisional wartime capital of Chongqing and other targets in Sichuan. According to incomplete statistics, a total of 268 air raids were conducted against Chongqing, involving anywhere from a few dozen to over 150 bombers per raid. These bombings were probably aimed at cowing the Chinese government, or as part of the planned but never executed Sichuan invasion. Opposing forces China The centralized command of the Republic of China Air Force integrated many former Chinese warlord air force aircraft and crews, and numerous Chinese-American and other foreign aviators volunteering for service with the Chinese Air Force. Nominally referred to as the Nationalist Air Force of China, at the outbreak of the air war in 1937 it was equipped mainly with US-made aircraft and training, as well as aircraft and training from other foreign sources, including Italian and Japanese army air force instructors. China was not an aviation industrial power at the time, and by the end of 1938 had suffered severe losses through attrition at the Battle of Shanghai, the Fall of Nanking, the Fall of Taiyuan, and the Fall of Wuhan. The Chinese had found new hope in the lifeline of the Sino-Soviet Non-Aggression Pact of 1937, and Chinese Air Force pilots had almost completely transitioned into the Soviet-made Polikarpov I-15 and I-16 series of fighter-pursuit aircraft by early 1938. Along with a few remaining Curtiss Hawk IIIs which were China's frontline fighter-attack weapon of choice at the beginning of War of Resistance-World War II in 1937. A handful of other fighter-aircraft models were also available to the Chinese, including several Dewoitine D.510 fighters left by the defunct French Volunteer Group (the 41st PS), which was disbanded in October 1938 due to difficulties in combating the Mitsubishi A5M fighter. While the Chinese victory at the Battle of Kunlun Pass kept the Burma Road open, the ever increasing Japanese blockade of imports into China, particularly after Chongqing was cut off from the sea after losing Nanning in the Battle of South Guangxi, and with war