It started mostly because of the hate in the hearts of the Germans. After WWI the Germans hat to pay all of the reparations putting them into a depression making it easy for dictator Adolf Hitler take over. Once he was in control he started taking over neighboring countries.

There were 2 sides involved, the Axis and the Allied powers. On the side of the Axis powers were Nazi Germany ruled by Adolf Hitler, Japan ruled by Hideki Tojo, and Italy ruled by Benito Mussolini. On the Allied side was the United Kingdom whos Prime minister was Winston Churchill, France whos prime minister was Édouard Daladier, the soviet Union who was ruled by Josef Stalin, and The U.S. whos president was Franklin D. Roosevelt.

There were many contributions to the war but probably the most important was the introduction of nuclear warfare with the creation of the atomic bomb which could level a city in the mater of seconds.

There are 3 major events that occurred that played major roles in WW2 one of which being D-Day or operation overlord this was the plan of the usa to take back Europe by storming the beaches of Normandy, France. The last 2 event ended the war with Japan and introduced the deadliest bomb in history. This of course is the bombing of Hiroshima and Nagasaki. These bombings took place 3 days apart. Hiroshima was bombed on August 6, 1945 and Nagasaki was bombed on August 9, 1945.

The Allied Powers were the winners of the war

They won by bombing Japan which took them out of the war and closing in on Hitler until they were too close and he ended up commuting suicide and Italy stopped fighting after a forced surrender after allied powers invaded Italy

After the war all of Europe was in shambles most cities were covered in rubble because of the constant fighting and bombing

The real winners were the U.S.A. With Europe in pieces and trying to rebuild the U.S. was mostly untouched, other than Pearl Harbor which brought them into the war in the first place, making them able to build up the nation and make it great.