US P-61A Black Widow - During WWII, As the Air Forces of each country started paying attention to night bombing, the bombing became more effective than ever. To fight against night bombing, a series of night fighters were put into use. The US started their night fighter program in 1940. The Army used the P-70 Havoc and Beaufighter to fight with the Japanese until the first 45 P-61 Black Widows were in active service on October, 1943. The first 37 P-61 aircraft were installed with a four gun turret on the back of the fuselage and deleted on the following aircrafts. The first unit to take the P-61A into combat was the 6th Night-Fighter Squadron in Hawaii. The Black Widow soon replaced the Douglas P-70s and P-38J on 1 May 1944.