Weegy: The Japanese attack on Pearl Harbor brought the United States into World War II. User: which axis nation was knocked out of world war 2 first Weegy: Italy was knocked out of World War II first. User: when the united states entered world war 2 in europe, where were american forces first sent on a major offensive? Weegy: When the United States entered World War II in Europe, American forces were first sent on a major offensive to Northern Europe. (More)