After the declaration of war against Japan with the Pearl Harbor attack and after the declaration of war from Germany and Italy against the United States of America on the December 11, 1941, the president Franklin D. Roosevelt asked the Congress the declaration of war against those two same nations.
According to the american Constitution, it's the Congresso and not the president that has the power to declare war and after the president declaration the president has the job of using all the needed resources in order to achieve the victory.
Unlike what happened with the declaration against Japan, Roosevelt remained in the White House to lead the war effort in the role of Commander in Chief.
After the signing of the declaration by the President, Congress acted quickly and with unanimous vote. The resolutions passed by Congress were identical for both Germany and Italy.
Roosevelt's request that was later read in the national radio was the following:
«To the Congress of the United States:On the morning of Dec. 11 the Government of Germany, pursuing its course of world conquest, declared war against the United States.The long-known and the long-expected has thus taken place. The forces endeavoring to enslave the entire world now are moving toward this hemisphere.Never before has there been a greater challenge to life, liberty and civilization.Delay invites great danger. Rapid and united effort by all of the peoples of the world who are determined to remain free will insure a world victory of the forces of justice and of righteousness over the forces of savagery and of barbarism.
Italy also has declared war against the United States.I therefore request the Congress to recognize a state of war between the United States and Germany, and between the United States and Italy.Franklin D. Roosevelt»
Consequently, Congress issued a formal declaration of war:
«Declaring that a state of war exists between the Government of Germany and the government and the people of the United States and making provision to prosecute the same.Whereas the Government of Germany has formally declared war against the government and the people of the United States of America:Therefore, be it Resolved by the Senate and House of Representatives of the United States of America in Congress assembled, that the state of war between the United States and the Government of Germany which has thus been thrust upon the United States is hereby formally declared; and the President is hereby authorized and directed to employ the entire naval and military forces of the government to carry on war against the Government of Germany; and to bring the conflict to a successful termination, all of the resources of the country are hereby pledged by the Congress of the United StatesApproved, December 11, 1941, 3:05 pm EST»