[quote=@Eremul]
[@Snake Face] A knight works fine. I would still like him to be in charge of a company of mercenaries though -- 300-500 strong. Is that alright?
[/quote]

Ehhh let's say around 200, there weren't many large scale mercenary armies in England at this time I don't think, so yes 200-250.Is that okay?
Be mindful that any men you lose can be replenished by recruiting.
Say, I bet the Welsh, Irish, or the upcoming Baron's Alliance could use a small mercenary unit amongst their ranks.