Upvote:-2
You might want to consider following battles as bloodiest for British armies. Please note I am not considering a day-by-day casualties count, but the total casualties for a battle.
Some good candidates:
Upvote:2
List of battles by casualties
I have made a list using this wikipedia article named List of battles by casualties and have simply removed the ones involving Brits and put them in to order from one to five, and added one extra.
One to five