 During the Second Sino-Japanese War (1937–1945), the ROCAF participated in attacks on Japanese warships on the eastern front and along the Yangtze river and interdiction and close-air support during the Battle of Shanghai in 1937.The initially Chinese frontline fighter aircraft were mainly Curtiss Hawk IIs, Hawk IIIs and Boeing P-26Cs.These engaged Japanese fighters in many major air battles beginning on 14 August 1937, when Imperial Japanese Navy warplanes raided Chienchiao airbase; "814" has thus become known as "Air Force Day".