User blog comment:Longdead97/Ulfric's war effort & gaining support. Smart move or no?/@comment-5558140-20130324032553/@comment-80.216.216.52-20130327191200

And he killed Torygg to emphazise that the days of Solitude puppets were over.

See;

http://elderscrolls.wikia.com/wiki/Skyrim%27s_Rule