April of 1917 was the official American declaration of war on the Central Powers. Congress was driven to the decision by three things.
1. The 1915 sinking of the British Lusitania by German submarines. 128 of the lives lost were American.
2. The Zimmerman Telegram, which offered German aid to Mexico for an invasion of the US.
3. The speculation that if the Allied Forces lost, they wouldn't be able to pay America back.
The US did enter World War 1, though not till 1917.
1941
1917 smart
no
1917
Britain's side
It started in 1914
The Jews
1914
by Gerrnan submarine
The Titanic
No, World War 1 ended in 1918 and the attack on Pearl Harbor was on December 7, 1941. Pearl Harbor was the event that provoked the US to enter World War 2, not 1.