World War 2 was one of the deadliest wars in history, lasting from 1939 to 1945. It involved two main military alliances - the Allies (including countries like the US, UK, and Russia) and the Axis powers (led by Germany, Italy, and Japan). Some key events that shaped the outcome of the war included the Battle of Britain, Pearl Harbor, the Battle of Midway, and the Normandy invasion. Ultimately, the Allies were victorious, but over 60 million people lost their lives during the war, making it the bloodiest conflict in history.