24 juin 1812 - The French invade Russia, the start of the Patriotic War of 1812.

Description:

It started when Napoleon took his army and crossed the Neman river. They went back and forth in the war, until France took over Moscow. The russians retreated and got caught again. They reatreated once more, where they got caught in the harsh Russian winter, where they lost a majority of their army. This changed European politics forever.