There were a number of "casus belli" (Latin for "Causes of War"), but the ultimate reasons were based on Germany's policy of unrestricted submarine warfare.
The "Zimmerman telegram", a German diplomatic message addressed to Mexico, had proposed that Germany and Mexico should enter into an alliance in which previously Mexican territories such as Texas, New Mexico and Arizona would be restored to Mexico when Germany won the war. Mexico ignored the proposal, but the message was intercepted and decrypted by the British, who used it encourage the US to enter the war overtly on the side of Britain. This provided the final impetus for Congress to declare war.
The US did enter World War 1, though not till 1917.
The ozone hole in 1970's was a big one. It caused most to the UV to enter.
Hitler was not in world war one, he was the leader of the Germans in world war two.
Congress and the president also a lot of Americans wanted us to enter world war one
The two main factors that caused the US to enter World War II were the Japanese attack on Pearl Harbor on December 7, 1941, and Germany's declaration of war on the US on December 11, 1941. These events directly threatened American national security and forced the United States to take an active role in the war.
I think there are two respects, one for money and one for the sense of achievement.
The sinking of the Lusitania was a big one.
do you mean what caused us entry into world war one? if so then the sinking of the USS Lusitania by German u-boats was what caused American entry into the war
Ultimately gravity overcomes all other forces.
The beginning of the cease fire of World War One was all thanks to the Armistice of Compiégne.
Great Britain entered WWI because of the idea of collective security, where an attack on one country means an attack on all other countries in the alliance. Therefore, when Germany invaded Belgium, G.B declared war on Germany.
the flamer caused over 300 deaths in world war one