America was brought into WWII with the Japanese bombing of Pearl Harbor on December 7, 1941. WWII involved two theaters of war: a Pacific theater and a European theater. In 1942, the Battle of Midway erupted in the Pacific, which led to the United States and Allies developing the strategy of island-hopping. Japan responded to this new strategy by sending out under-trained Japanese pilots who led kamikaze attacks, in which the pilots deliberately crashed into Allied ships that resulted in a suicide collision. The Japanese made use of soldiers that were willing to fight to the death and sent balloon bombs into the United States. The American victory at Midway put Japan on the defensive for the rest of the war, but Japan was able to gain control of the Philippines and after MacArthur was forced to abandon the island, he vowed to return. MacArthur fulfilled his promise and returned two and a half years later, where he landed on Leyte and liberated the Philippines.