1. When did the U. S. enter WWII and why did they end their period of isolation to enter the war?​

They entered the War April 2, 1917. There's a couple of reasons why they enetered.

Explanation:

As a neutral nation, the United States sought trade with both sides in the war. Both sides needed goods of all kinds, and American businesses were happy to provide them. However, Britain's blockade made trade with Germany difficult. The British navy stopped and searched American ships headed for German ports. Often, they not only searched the ships, but seized the goods they carried. The United States complained its ships should be free to pass without interference. The British responded that they were fighting for their survival. While blocked from trade with Germany, the United States continued trading with Britain. In fact, American trade with the Allies soared. In addition, Great Britain and France borrowed billions of dollars from American banks to help pay for their war efforts. All this business caused an economic boom in the United States. It also upset the Germans, who watched the supposedly neutral United States helping the Allies.

Dramatic events continued to push the United States into the war. First, in March 1917, a revolution took place in Russia. The Russian people overthrew their monarchy, which was headed by the czar. In place of the monarchy, the Russians set up a temporary government promising free elections. The new Russian government also vowed to continue the fight to defeat the Germans.

This change in Russia from an autocracy, in which one person with unlimited powers rules, to a more democratic government raised Allies' hopes. Wilson could now argue that the Allies were fighting a war for democracy, making public support for war more likely.

The U.S. officially entered WW2 in 1941. After the Pearl Harbor Attack.

Explanation

They ended the period of long running isolation due to the attack on Hawaii's Pearl Harbor. This attack destroyed 20 of our ships,300 of our airplanes as well. 2,403 sailors died during the attack and 1,00 people were wounded.

-We entered the war because we were personally attacked and Amercain lives were lost.

im the bozz no matter what

the term is einsatzgruppen