Battle of Waterloo.
The diagram on the right shows the initial disposition of the Anglo-Dutch army under Wellington (red) and the French Army under Napoleon (blue). You can see how they got there by reading my earlier posts [Thursday, June 15, 1815 , Friday, June 16, 1815 , and Saturday, June 17, 1815 ].
There are many detailed descriptions of the battle online so I'm not going to bother with details. The French armies had to eliminate the fortified positions at Hougoumont, La Haye Sainte, and Papelotte. They succeeded at La Haye Saint and Papelotte but the British held on to Hougoumont. This is one of the decisive skirmishes of the battle. The French committed far too many troops to the attack on Hougomount and wasted far too much time.
I've been to the battlefield twice. Here's a photo from 2010 when I went with my daughter, son-in-law, and newly born granddaughter. The big hill behind them was made for tourists so they could get an overview of the battlefield from the top. Most people think it ruined the site.
There are monuments to various military leaders all over the battlefield. Most of the thousands of men who died that day have no monuments to mark where they fell. One of Ms. Sandwalk's distant cousins, Isabella Hood, was married to John Whyte of the British Dragoons. He died at Waterloo. His wife moved to Canada.