They were invented and introduced just prior to the United States entry into world war two.
They supported the war effort and joined the military in large numbers
America was a late and reluctant entrant into the Great War. It was thrust into WW-II by the Japanese attack on Pearl Harbor.
pretty much everywhere in Germany and the united states
United States Submarine Operations in World War II was created in 1949.
To delay the United States' participation into World War 1, giving Germany better chances to win the conflict. The proposal was intercepted by British forces however, and relayed to the United States. It hastened America's entry into WW1, eventually resulting in Germany losing the war.
The isolationism of the United States delayed its entry into both World Wars.
They were invented and introduced just prior to the United States entry into world war two.
The Japanese attack on Pearl Harbour 7 December 1941.
The attack on Pearl Harbor was the factor that made the United States decide to enter the war.
Wilson did use that term to indicate that the United States had an obligation to lead the free world, ie., democratic governments. But that goal was only a part of the reasons for the US entry into World War 1.
The sinking of the Lusitania was the spark for US entry into WW I.
They supported the war effort and joined the military in large numbers
Invade Europe and defeat Germany.
The Zimmerman telegram was published in the United States on March 1, 1917. It was a coded telegram asking Mexico to join Germany's side on World War I and Germany promised that if they join them that they would get their lost and back from the United States. Here is what they lost to the United States: New Mexico, Arizona and Texas. The zimmerman Telegram was the last straw for the United State and on April 6, 1917 the United States declared war on Germany.
The largest factor was Germany's program of unrestricted submarine warfare; even attacking neutral ships in British waters, resulting in the deaths of many Americans.
The attack of Pearl harbor and then the united states got word of what hitler was doing to the Jews and so we invaded