This time lapse video 'World Battleground: 1000 years of war in 5 minutes' by Kolomaire via YouTube is an animation showing important battles. The sizes of the explosions and labels are proportional to the number of casualties. 

Tip: If you can’t last the full 5 minutes, fast forward to the 4 minute mark to see the more recent battles and their size and scale relative to conflicts in history.