User blog comment:Harold Burned-Mane/The Truth about Ulfric Stormcloak/@comment-17114085-20130912151507/@comment-17114085-20130913023438

It doesn't matter if in other cities the races live in harmony Windhelm is different, there is a lot of tension between the three races there. Like i said the dunmer in Windhelm ( example Suvaris Atheron ) don't like the argonians, just like the argonians in Windhelm don't like them back.

The official start of the Civil War was 4E201 when High King Torygg was killed but the nords and the Legion have probably been fighting for a while, again lots of tension between them.

Your last point may be right, its very possible he did it to appease the nobles though can't be confirmed. That is the problem with Skyrim lore lots of it was left out (either because bethesda was being lazy or it was intentional to keep fans speculating).

Talos guide you-Harold Burned-Mane