After launching their Pacific War, the Imperial Japanese Navy managed to infiltrate New South Wales waters and in late May and early June 1942, Japanese submarines made a series of attacks on the cities of Sydney and Newcastle. Though casualties were light, the population feared Japanese invasion. The main Japanese naval advance towards Australian territory was however halted with the assistance of the United States Navy, in May 1942, at the Battle of the Coral Sea. The Cowra breakout of 1944 saw Japanese prisoners of war launch a suicidal escape attempt from their camp in the Central West of New South Wales. This is considered the only fighting within New South Wales of the war.