During his long life Jan II led the already small Duchy of Opole to a significant economic development.

After hearing the news about this events in Nysa, Jan II decided to avenge his brother's death and began to gather troops in order to make a brutally retaliatory expedition against Cieszyn.

Thanks to the increased debts of several Silesian rulers, within only a few years the Duke of Opole became in the owner of almost the majority of Upper Silesia.

The formal contract of mutual inheritance was performed in 1511 between the childless Duke Valentin and Jan II.

Since the beginning of his reign, Jan II was in favor of the Polish culture, maintain regular contacts with Kings John I Albert, Alexander and Sigismund I the Old.

Jan II, with due regard to the economic development of his domains seemed to granted many privileges, gained fame with the largest 72 articles of the called Ordunek Górny on 16 November 1528 issued in Opole, which was a privilege to develop the mining in the Duchy, which a considerably diminution of the Duke's treasure.

Initially, the slightest chance of be declared heir of Jan II was to George, Margrave of Brandenburg-Ansbach.

The death of Louis II and the succession of Ferdinand I of Habsburg in the Bohemian-Hungarian Kingdom put in jeopardy the chances of George of Brandenburg.

Only after the sign of a treaty in Prague on 17 June 1531 and the payment of 183,333 guilders to King Ferdinand I persuaded him to accept the candidacy of the Margrave of Ansbach.