everything i have ever read about Towton reports that it was a horrible battle. if the lancastrians were routed, then tried to escape, their armor and the snow storm would have slowed them down, and the attacking cavalry would have killed thousands. trying to run away in a snow storm wearing armor, with cavalry attacking you, would lead to lots of deaths.
i have no agenda of playing down the horror of this battle--one of my ancestors fought in the battle and was knighted by the Yorkists, so i am very proud of this.
however, i would like to see some objective evidence before i would be willing to accept the 28,000 dead figure.
i really don't know if the 28,000 is based on objective evidence (e.g. skeletons), which is unlikely; historical writings, which are likely to be inaccurate; or just on somebody's say-so.
The length alone (unusual for any battle using only brute human strength with edged weapons and without reinforcements) is telling, and I suspect a large number of wounded (given the weather) would have succumbed to the elements.
Your ancestor must have been one heck of a warrior to have made it through that battle.
According to the physical anthropoligists, most of the skeletons show the kind of bone growth and injuries we only associate today with athletes. These guys were born with a sword in their hands and must have spent thousands of hours in practice and lugging their arms and armor around England.
"On the Kyngys parte is slayn Lord Fitzwater, and Lord Scrop sore hurt. John Stafford. Horne of Kent, ben ded, and Vmfrey Stafford, William Hastyngys, mad knyghtys, with oþer; Blont is knygth, &c. Vn the contrary part is ded Lord Clyfford, Lord Nevyle, Lord Welles, Lord Wyllouby, Antony Lord Scales, Lord Harry and be supposyng þe Erle of Northumberland, Andrew Trollop with many oþer gentyll and comons to þe nombre of xx ml. Item, Kyng Herry, the Qwen, the Prince, Duk of Somerset, Duke of Exceter, Lord Roos, ben fledde in-to Scottelond, and they ben chased and folwed, &c. We send no er vn-to you be-cause we had non cer[teyn tyd]yngys tyl now; for vn-to þis day London was as sory cité as mygth, and be-cause Spordauns had no certeyn tydyngys we thougth ye schuld take them a worthe tyl more certayn. Item, Thorp Waterfeld is yoldyn, as Spordauns can telle you. And Jesu spede you. We pray you that this tydyngys my moder may knowe. Be 3owre broder W. Paston Th. Playter Comes Northumbr' Comes Deuon' Dominus de Beamundo Dominus de Clifford Dominus de Neuyll Dominus de Dacre Dominus Henricus de Bokyngham Dominus de Welles Dominus de Scalis Antony Reuers Dominus de Welluyby Dominus de Malley Radulfus Bigot, miles Millites Sir Rauff Gray Sir Richard Percy Sir Harry Belyngham Sir Andrew Trollop With xxviij ml nomberd by harraldys" (emphasis mine)
There is a river to the north of Towton, the Cock, not all that deep but with steep banks. The retreating Lancastrians were trapped at one of the few fords in the vicinity of the battleground and dispatched accordingly.
Probably the most important reason for the high percentage of casualties was King Edward's call for no quarter.
http://www.yorkshirehistory.com/towton/towton1.htm
Romans had a battle way back when in England with 100,000 killed mostly locals, Roman casualties in the hundreds.