While the Lithuanian magnates and szlachta hesitated, the Poles forced the issue, by the administrative sleight of hand of transferring Lithuania’s Ukrainian lands from the Grand Duchy and annexing them to Poland. The Senate and Sejm of Lithuania and those of Poland met at Lublin on the border between the two states, and on 1 July 1569 unanimously swore a new act of union. At the practical level, the Union of Lublin was hardly revolutionary. It stipulated that henceforth the Sejms of both countries should meet as one, at Warsaw, a small town conveniently placed for the purpose. The combined upper house would contain 149 senators and the lower 168 deputies. Poland and Lithuania would share one monarch, not, as had been the case hitherto,
now formally became ‘the Most Serene Commonwealth of the Two Nations’, ‘
There was an obvious paradox in the co-existence of monarchy and republic, yet the Poles made a virtue out of the seeming contradiction. The political writer Stanisław Orzechowski claimed that the Polish system was superior to all others, since it combined the beneficent qualities of monarchy, oligarchy and democracy. That it might combine their faults as well was not considered. In spite of continuous efforts by the executionists, the relationship between these three elements was never precisely defined. In principle, the Sejm was the embodiment of the will of the people, and therefore the fount of legislative power; the Senate were the custodians of the laws; the king was both a political unit in his own right and the mouthpiece of the Sejm. While the Sejm had curtailed the monarch’s personal power, it meant to invest its own in his person, thereby turning him into its executive. The would-be oligarchs in the Senate resisted this aim, while the uncertainties attendant on the Reformation and the impending interregnum made the deputies hesitate before placing too much of their power in the hands of the king.
There was never any question of doing without a king. The Sejm had debated what to do on the death of Zygmunt Augustus as early as 1558. Because of the stalling tactics of the Senate, nothing had been formally agreed when, on 7 July 1572, the last of the Jagiellons died. The burning issue thus became how his successor should be chosen, and by whom. Early suggestions on procedure envisaged an enlarged Sejm, where each member would have one vote. The eleven major towns were to be represented, but not the bishops, since they were agents of a foreign power.
When the time came, the Senate demanded the exclusive right to elect the new king, which brought an angry response from the szlachta. A suggestion that the entire political nation should have an equal vote was seized on by the bishops, who realised that an overwhelming majority were Catholic and therefore likely to support a Catholic candidate. The cry for universal suffrage was taken up by an ambitious young deputy to the Sejm, Jan Zamoyski, who captivated the szlachta with his rhetoric and became their tribune. With their support, he forced the proposal through the Convocation Sejm which met after the king’s death, in 1573. From now on every single member of the szlachta, however poor, was a king-maker. More than that: each one carried a royal crown in his saddlebag, for it was stipulated that only a Polish nobleman or member of a ruling foreign dynasty could be a candidate to the throne of the Commonwealth.