California during World War II was a major contributor to the World War II effort. California's long Pacific Ocean coastline provided the support needed for the Pacific War. California also supported the war in Europe. After the Japanese attack on Pearl Harbor, Hawaii, on December 7, 1941 most of California's manufacturing was shifted to the war effort. California became a major ship builder and aircraft manufacturer. Existing military installations were enlarged and many new ones were built. California trained many of the troops before their oversea deployment. Over 800,000 Californians served in the United States Armed Forces. California agriculture, ranches and farms were used to feed the troops around the world. California's long coastline also put the state in fear, as an attack on Ca