eeyup, or at least it had been a very long time between the two events. The invasions from Black Marsh to Morrowind happened just before or during the very beginning of Titus Mede I's rule (very early in the beginning of the era), while The Great War happened during Titus Mede II's rule, which was 35 (30?) years before Skyrim.

With The Red Year, it was a time to strike the dunmer, not have it happen and do nothing. Plus, the argonians are not buddy buddies with the Thalmor, as they did kick them out after they took over portions of Morrowind that had been fought over for a very long time.

Ok fair enough. It has been a long time then but (play devil's advocate a bit) considering the (natural) life expectancy of mers, is it not an inconceivable to be some Thalmor/Hist related ploy? Two provinces already taken out of the equation even before the Great War. We don't know (or if we do, please tell me) the scope of the Thalmor's machinations and subterfuge and they're happiness to wait and see what happens now there's a Skyrim civil war seems to me that they enjoy a long game of chess. Will have to read up on when the Argonians split from the Empire too; although surely they would invade Morrowind whilst still being a part of it?

Mind you if Argonian Invasion did happen so soon after the 4E started then it would have to be extremely quick thinking on the Thalmor's behalf to try and take out Morrowind and neutralise Black Marsh, especially as they were still spreading their message of heroism and saviours to the Altmer of SI at the time?

I think that last part especially is right. The first potential Thalmor action is in 4E10, which is when they still didn't truly rule Summerset. This is still after the invasion of Morrowind and in a time when they were still trying to gain power. The Black Marsh had already succeeded from the Empire back in 4E1. The Thalmor didn't really get power until 4E22. So it could all have happened it's just incredibly unlikely. Also as stated above the Argonians had many reasons to invade Morrowind none to do with the Thalmor. The red year gave them a perfect time to do this.