The treachery reported in the accounts of the battle itself could quite reasonably be explained by the action of the Stanleys alone. After all, there are various instances in other conflicts where one or more battles failed to engage the enemy, yet where there can be no question of treasonable intent. For example, in the devastating Scottish defeat at Flodden there were two Scots battles that did not come to handstrokes.²⁰ At Bosworth we may now have a simple but very powerful tactical explanation for Northumberland’s inaction. If his battle was deployed behind the marsh then he will have been unable to attack the rebel vanguard as it advanced across the front of his battle for, as Polydore Vergil so eloquently explained, the marsh acted as a ‘fortress’ protecting the rebel right flank. If Norfolk now swung his battle around to face south-westward, to counter Oxford, no space will have been left for Northumberland to attack around the north of the marsh. But on the south he was either hemmed-in by the Stanley battle or, if the latter stood off further to the south, he will have been wary of being attacked from the flank or rear by Stanley if he manoeuvred south of the marsh. This is only a hypothesis but, if correct, it provides the crucial tactical flaw in Richard’s deployment that may have cost him the battle.