1324 Marco Polo - Venetian merchant and adventurer. He travelled from Europe to Asia for a 24-year period lasting from 1271 to 1295, remaining in China for 17 of those years. Polo excelled all the other travellers in his determination, his writing, and his influence, reaching farther than any of his predecessors, beyond Mongolia to China. His Il Milione (The Million), known in English as the Travels of Marco Polo, is a classic of travel literature

This doesn't have anything to do with Marco Polo himself, but why was the pool game named Marco Polo and how do you play it? I've always been curious.

1877 Crazy Horse and his warriors fought their final battle against the US Cavalry in Montana.

I enjoyed seeing the monument to Crazy Horse, even though it isn't near completion, better than I did Mt. Rushmore. It is massive and very impressive.

1969 A panel of the National Academy of Sciences agreed there was no evidence that UFO's are intelligently-guided spacecraft from beyond Earth

I question their expertise.