The attack on Pearl Harborimmediately galvanized a divided nation into action. Public opinion had been moving towards support for entering the war during 1941, but considerable opposition remained until the attack. Overnight, Americansunited against the Empire of Japan inresponse to calls to "Remember Pearl Harbor."
Many Europeans had experienced the tyranny of monarchies in their own countries. The Patriots' war against George III inspired them. Lafayette and Pulaski may have also been moved by the ideas in the declaration of Independence. I hope this helps you