Quote Originally Posted by KrooK
Gustav was bad general. He was winning in Poland because Poles very weakened by previous wars with Russia and Turkey. Later he lost some battles with Poland and finally Sweden gave back every port they took.
A bit biased? The Swedish gave back all the ports taken in Poland as it was part of the deal. Sweden would own town/city X and extract taxes and - more importantly - duties therefrom for Y amount of years.

Gustavus has my vote at least. Although Mauritz of Oranien was the one who really developed the tactics used by Gustav.