December 8, 1941- President Franklin Delano Roosevelt and Congress agree: The U.S. must declare war on Japan. Two days later, we will declare war on Germany and Italy as well. The U.S. has entered World War II. For nearly four years, its effects will be felt in every community across the country. More than 20,000 men and women from Mecklenburg County will serve in the U.S. military during the war.