Pity about the endorsement on the cover!
I assumed you were talking proportionately but looking it up was staggered to see 28 000 killed. That is horrendous.
I've never spent long enough on the Wars of the Roses to get it straight in my head - read a good overview a couple of summer's back as a result of walking over what little is left of Tewkesbury. But it's now got jumbled again.
Wars of the Roses. The 'Roses' thing came later - not called that at the time, apparently. Nor did they all go around wearing red and white roses. As for causes - looks like the combination of a total incompetent/mad King (Henry VI) making a complete mess of his kingship (having been crowned king at age 9 both of England and -in Paris- of France, thanks to his Dad's legacy ), finally losing the French 'territories' and a whole heap of rivalry for influence that basically resulted in a battle to the death between armies drawn largely from the North (Lancaster) and South (Yorkists) at Towton. Something like 10% of the UK male population fought on that field that day. And Margaret of Anjou's power base was obliterated as a result.
Arguably, we are still living with the consequences of this one! (thanks to the Yorkists winning - close thing, the weather advantage on field of battle swung it). And the recent archeological finds are staggering - evidence of acts not dis-similar to Kosovo and the like.
David Starkey - really knows his stuff. The 'Introduction' he adds to this book helps considerably with regards to background/context.