After the united states declared war to germany approximately how long did it take for over a million americans troops to arrive in europe?

It took one year for over a million Americans troops to arrive in Europe after the United States declared war to Germany.

On 11 December 1941, four days following the Japanese attack on Pearl Harbor and the United States declaration of war against the Japanese Empire, Nazi Germany declared war against the United States, in reaction to what was considered to be a series of provocations by the United States government when the US was still officially neutral during World War II.

On December 11, 1941, the United States Congress declared war upon Germany, hours after Germany declared war on the United States after the attack on Pearl Harbor by the Empire of Japan.