On this day the Battle of Hastings was fought.
The battle lasted all day, unusual for this time, and both sides had approximately 7000 men. Most scholars agree that, if Harold had waited a few days while more of the fyrd and nobles gathered to his banner, he would have had a much better chance of defeating William.
The outcome changed English history, but even more it changed the English language. It marks the effective end of the Old English period, and the beginning of the Middle English period.
You can view the entire Bayeaux Tapestry here ( you will need to enlarge it in most browsers )