Do you think that William the Conqueror would have lost at the Battle of Hastings if Harald Hardrada and Tostig Godwinson had not attacked right before William?
Hastings was a very closely fought battle that Harold Godwinson and many troops fought in after another battle and a long march.
I have no doubt that Godwinson would have won if it was fought first.
Note that both Harald Hardrada and William the Bastard assembled their armies and fleets around the same time. One to the north, one to the south.
They waited for favorable winds. The winds first blew to the south. That is what decided England’s future. If they had blown to the north first, it’s a whole 'nother ballgame.
Was there any kind of coordination between the two invading armies? Or was it just a given that both would be invading at some point?
My understanding that the death of Edward the Confessor set off a race to see who could invade fustest with the mostest. Harald Hardrada just happened to win (in his case, the prize being “six feet of English soil, or perhaps a bit more as he is taller than most men”).
Anti-coordination. Both men had claimed the throne of England. If Harald Hardrada had landed a few weeks later, William would have marched north to fight him just as Harold Godwinson had.
As it was William had to fight off landings on the north coast by another Scandinavian claimant, Sweyn II of Denmark( a nephew of Cnut )in 1069/70 and 1074/75.
ETA: I don’t think it is foregone conclusion William would have lost against a full-strength Harold Godwinson. After all Hardrada won at Fulford and when he lost at Stamford it was largely due to being caught flat-footed. Medieval pitched battles were chancy things and both commanders were capable.
I do agree it would have been rather more likely than not, however.
Just the fact that both thought they should be the rightful King of England alone tells you that they were hardly working together.
Perhaps I am just poorly read on Hastings, but I’ve always been impressed by Godwinson’s intelligence service (or scouting/spying). Somehow he knew both invasions were coming (or found out quickly). He was able to use what future military strategists would call “interior lines” to strike each invading force separately, instead of being surprised and ambushed by them. As far as strategy goes, he won the campaign.
And that’s how far strategy goes. He lost Hastings tactically – narrowly lost, closely fought, but ultimately a loss, and that collapse lost everything, despite his strategic upper hand.