The unprovoked attack on Pearl Harbour by the Japanese
Trojan horse
The atomic bomb
The assassination of Archduke Ferdinand was the one event that pushed Europe over the edge and brought about World War I.
The attack on Pearl Harbour, by the Japanese, directly brought the USA into the second World War. America declared war on Japan, and then Germany declared war on the USA, some days later.
Another world war
World War II
World War II
The Cuban Missile Crisis is the event that brought the world closest to a nuclear fallout.
World War II brought the end of colonialism.
It is due to the balkans problem
The Japanese attack on Pearl Harbor brought USA into the war.
I think when Adolf Hitler was untrue to a treaty .