Ohhh. Good question. I like some of the answers already here so I will name something different.

For me, it would likely be something from WW2. I will say the Battle of Okinawa. Watching Desmond Doss save all those lives without firing a single shot after being heckled by those same men. Wow.

D Day would be up there as well. It is odd to pick such sad moments, but they would make me appreciate our freedoms more than I do.