Mournhold was sacked by Mehrunes Dagon during the 80 year war. This was not something the Empire did....

Also, the Mournhold sacking in The Real Barenziah did not happen during the four score war, that was during Tiber Septim's conquest.

Yeah actually I'm still confused by that...

I mean it could have happened, but in Morrowind it always sounds like the province surrendered before the war came to full conclusion, then in the Real Barenziah and the biography of Barenziah it sounds like the province was completely ruined by the Imperial forces. Also in the Real Barenziah there is no real mention of the Tribunal fighting at all, when in Morrowind we do hear about them fighting against Dagoth Ur in earlier years and their decision to not want to fight on two fronts. Vivec makes it sound like he signed the peace to avoid fighting both at the same time, not like he was fighting both at the same time and then figured it was a bad idea...

Then in http://www.imperial-library.info/content/morrowind-imperial-province it doesn't sound like there were any battles at all. Or rather states that a peace was made before fighting even started. This just confuses me... Given the most recent evidence we have, I feel it's rather safe to say that Mournhold wasn't sacked by the Empire at all. Just that Barenziah was taken from her home as a peace deal.

Indeed, it does not really fit in. How's about "that was allegedly during Tiber Septim's conquest" instead?

Tiber Septim wouldve been forced to drop the A bomb

The Real Barenziah is originally from Daggerfall, so that might explain why it doesn't really mention the Tribunal and presents a different view on the war.