score:4
The short answer is: loot them.
Once the bodies had been looted, they would be left to rot. There is a famous passage in Herodotus concerning the Battle of Pelusium which had occurred about 75 years previously:
On the field where this battle was fought I saw a very wonderful thing which the natives pointed out to me. The bones of the slain lie scattered upon the field in two lots, those of the Persians in one place by themselves, as the bodies lay at the first- those of the Egyptians in another place apart from them.
Many similar accounts of old battlefields could be listed.
As far as "escapees", that did (and does happen). In some cases the winning army will have soldiers make sure all of the enemy are dead and this can be combined with looting activities.