Abstract
This article discusses the correspondence of Nicolaus Olahus from the perspective of power relations and the creation and maintenance of networks of political influence in an age of dramatic changes following the collapse of the Kingdom of Hungary, as a result of the death of King Louis II in the battle at Mohács. The letters sent or received by Olahus between 1527 and 1533, while he was following the widow queen Mary of Hungary in Central and Western Europe, suggest his active role in promoting and maintaining vivid contacts with his friends, former members of the government of Louis II, who faced difficult dilemmas concerning their political allegiance. While many of them were initially members of the party supporting Ferdinand I of Habsburg on the throne of Hungary, the successful return of John Zápolya from his retreat in Poland, in 1529, with Ottoman aid, and the inability of Ferdinand to provide sufficient military support for defending Hungary, rendered their pro-Habsburg attitudes very risky. Olahus maintained his connections with his friends in Hungary in a time when serving John Zápolya seemed to be the most straightforward solution to many of them. The article analyzes the connections of Nicolaus Olahus with Emeric Kálnai, Bishop Thomas of Eger, Nicholas Gerendi, bishop of Transylvania, etc.. The article argues that Olahus used his personal connections in order to persuade his friends to join the Habsburg party in the years of confrontations between John Zápolya and Ferdinand I of Habsburg for the control over Hungary. In so doing, he was applying methods of creating and maintaining networks of political influence, mainly through the mechanisms of patronage, whose skillful use was recently recognized by the scholarship analyzing the political activity of queen Mary of Hungary as regent of the Low Countries.

Keywords
friends, networks, political influence, Nicolaus Olahus, Hungary, Transylvania