This article discusses the organizational and administrative structure of the Polish–Lithuanian Commonwealth. The Polish–Lithuanian Commonwealth was a confederative aristocratic republic of the period 1569–1795, comprising the Kingdom of Poland, the Grand Duchy of Lithuania and their fiefs. The Commonwealth was governed by the Parliament (Sejm) consisting of the King, the King-appointed Senate (Voivodes, Castellans, Ministers, Bishops) and the rest of hereditary nobility either in person or through the Lower Sejm (consisting of deputies representing their lands). The nobility's constitutional domination of the state made the King very weak and the commoners (burgesses and peasants) almost entirely unrepresented in the Commonwealth's political system. Classification The Commonwealth's administrative system was a pre-bureaucracy. In terms of Max Weber's tripartite classification of authority, it was, as with other contemporary monarchies, largely based on "traditional domination". There was, however, evidence of "rational-legal authority" in the nobility's respect for laws such as the Pacta conventa. Senatorial offices The Privy council and Upper chamber of the First Commonwealth’s Sejm (parliament, or diet) was the Senat (now Senate), comprising Bishops, Voivode, Castellan and ministers (central officials). The list of dignitaries eligible to serve in the Senat had been finalized when, in the Union of Lublin (1569), the Kingdom of Poland and the Grand Duchy of Lithuania were transformed into the confederal state of Crown of Poland and Grand Duchy of Lithuania, the Polish–Lithuanian Commonwealth. The most important official was the Primate, who was the Archbishop of Gniezno. From 1572, the first time that Poland had been without a king (the Jagiellon Dynasty having died out with King Zygmunt II August), the Archbishop of Gniezno served as interrex, i.e., as interim head of state until a new king could be elected. He represented the country and prepared elections for a new king. In addition, the Archbishop of Gniezno had the power to call a new Senat session, if he deemed it important to do so, even in the absence of the King. He could also invoke the "de non praestanda obedientia" article, giving the country the right to legally depose the King. From among other senators, he chose his own court marshal (often a Castellan). That person acted as the Archbishop's messenger during Senat meetings, giving signs (by moving a cross) that conveyed how the Archbishop wished his allies to vote. The Archbishop of Gniezno had two deputies: the bishops of Wrocław and Poznań. Of secular Senators, the foremost