Clearly WWII had a huge impact world wide-
throughout all nations people were deployed to go fight, whether volunteered or chosen with no choices
After WWII The US fell into a decline, soon after it went through the Great Depression.
Worldwide, well, 6 million Jews alone were murdered, as well as anyone thought to be gay, disabled peoples, gypsies, and sometimes just people who weren’t thought to be a purebred aryan.
Countries such as Austria and Holland were taken over and near destroyed.
But a good impact was the many allied nations there were. See countries such as the US, France and Britain were all on the same side, fighting against the Germans.