The Doom of the Noldor

[Kuruharan]

There are cases when to divide your forces is a better course of action.

That is very true. And as a matter of fact this may have been one of the times.

Would the Elves could have fared better of even won the day if they had been able to assemble into one host?

I doubt it. They could have broken into Angband if they had gathered all of their might, but then they would have been fighting inside Angband and I don't think they would have fared well. Probably the best thing that they could do is try to draw Morgoth out so that they could destroy his forces on ground of their own choosing. However, I fear that the best case scenario for them would be to re-establish the Seige of Angband after destroying as much of Morgoth's armed might as they could. I just don't think they could beat Morgoth inside his own massive fortress.

(It may be that I am overestimating the strength of Angband and underestimating the strenght of the Noldor. Or it could be that I am too accepting of the Doom of Mandos as being insurmountable in face of the way things actually turned out rather than how they could have turned out.)