Board Thread:Lore Discussion/@comment-4057475-20130710075111/@comment-6881629-20130729084807

Acording to the ancient Skaal basicly yes. Vahlok found out Miraak was going to betray the Dragons so he confronted him and they fought for days (this is how Solstheim became a island) before Vahlok could finish Miraak Mora took Mirrak. For his loyalty and bravery Vahlok was made ruler of Solstheim and swore to watch for Miraaks return. the skaal also say he was a wise and just leader.

That is a legend though so may not be entirely true but by all acounts Vahlok was very loyal to the Dragons and powerful enough to put up a fight against Miraak.