Would a Stark/Stannnis alliance have won the Iron Throne?

[Alester Florent]

from a military standpoint it makes sense doesn't it? If he is the first one to declare that gives Tywin the option to focus on Stannis (who is the only one who truly scares Tywin and the beggining IIRC) who would be completely outmatched. If I am remembering the timeline correctly its, Robb calls his banners then Renly declares (I cant recall if Robb has already rescued riverrun) then Robb declares then Stannis. If Stannis declares first Tywin would not be occupied in the RL and Stannis doesn't have the power to face hi in open warfare yet. So if Stannis doesn't have the power he doesnt have the option of declaring yet IMO

From a military standpoint it might conceivably make sense, although I'm not convinced. Stannis, being based on Dragonstone and with the largest fleet on the east coast, is pretty much invulnerable to attack early in the war. He can say whatever he likes and nobody can really do a lot about it.

From a political standpoint, though, not declaring early is a disaster. He might not have predicted Renly would challenge Joffrey, but the longer he waits, the more people will recognise Joff. And the longer he leaves the Northmen to fight and the Riverlanders to die without trying to make common cause with them, the less likely they are to recognise his claim when he finally issues it.

The longer Stannis delays, the longer he gives Tywin to assemble a loyalist coalition, and the more space he leaves for an alternative anti-Lannnister challenger to emerge. Which is exactly what happens, in the shape of Renly. While it's unrealistic to say that Renly was waiting for Stannis, his claim does look like it was cobbled together at the last minute in the absence of anyone else taking up the anti-Lannister cause. Had Stannis declared early enough and done the deal with Renly that he later offered, making Renly his heir, he might well have gone for it and been able to bring the Reach with him.