The story of Bona Sforza is examined, in this essay, in the context of the relations between the European states of the first half of the ‘500, in particular the Empire and the Catholic Monarchy of Charles V and of Philip II. The Queen of Poland and Duchess of Bari attempted to carve out a leading role in the international relations of the time, but had to succumb to the wishes of the two Habsburgs, interested in regaining control of the Duchy of Bari and intertwining anti-Turkish alliances with Sigismondo II of Poland, the son of Bona.