Q Had Harold prevailed in 1066, could the Normans have invaded England again, with papal backing?
No. In the first place, had William A
been defeated, he would almost certainly have been killed, like the other unsuccessful invaders of 1066, Tostig Godwineson and Harold Hardrada. In pre-Conquest England, there was no tradition of sparing defeated enemies.
But even assuming William had escaped and returned to Normandy, there would have been little chance of a repeat performance. The invasion of 1066 had stretched Norman resources to the limit. Ships had been built from scratch, supplies stockpiled for months, and mercenaries recruited from all over France and beyond. From a purely practical point of view, repeating all of this would have been hugely difficult.
The greater difficulty, which would surely have nixed any thoughts of a repeat attempt, would have been the lack of political support. Many Normans had objected to William’s plan to invade England in 1066, pointing out that it was insanely risky and that they were not obliged to serve him overseas. That would have been doubly true if a first attempt had failed.
Pope or no pope, by invading England in 1066, William had essentially submitted the justice of his claim to divine judgment. Had Harold prevailed at Hastings, contemporaries would have understood that God had decided against William.