On December 7, 1941 the American naval base, Pearl Harbor was attacked by the Japanese. The attack destroyed many American ships, planes, and lives which forced FDR to declare war on Japan the next day.
On February 19, 1942, FDR signed the Executive Order 9066. He established camps where Japanese Americans living close to military bases were forced to live by FDR's Army.
120,000 Japanese Americans forced out of their homes in the west into slum-like neighborhoods, called internment camps. They were only allowed two suitcases of their belongings.