Why don't war paintings show much blood/fighting/the reality of the situation? Is there a reason?

I am currently studying the battle of waterloo. I have noticed that in many of the paintings and records of the battle, there is not much blood or what you would have thought to have found on a battle sight. I feel like the painters are trying to dress the battle up as a positive, honorable time. When actually, a lot of people died and were injured!