Sigismund II Augustus (1520-1572) was the only son of Sigismund I the Old., king of Poland, whom he succeeded in 1548, and Bona Sforza. At the very beginning of his reign he came into collision with the turbulent szlachta or gentry, who had already begun to oust the great families from power. The ostensible cause of their animosity to the king was his second marriage, secretly contracted before his accession, with the beautiful Lithuanian Calvinist, Barbara Radziwill, daughter of the famous Black Radziwill.
But the Austrian court and Sigismund's own mother, Queen Bona, seem to have been behind the movement, and so violent was the agitation at Sigismund's first diet (October 31, 1548) that the deputies threatened to renounce their allegiance unless the king instantly repudiated Barbara. This he refused to do, and his moral courage united with no small political dexterity enabled him to win the day. By 1550, when he summoned his second diet, a reaction in his favor began, and the lingering petulance of the gentry was sternly rebuked by Kmita, the marshal of the diet, who openly accused them of attempting to diminish unduly the legislative prerogative of the crown. The death of Barbara, five days after her coronation (December 7, 1550), under very distressing circumstances which led to an unproven suspicion that she had been poisoned by Queen Bona, compelled Sigismund to contract a third purely political union with the Austrian archduchess Catherine, the sister of Sigismund's first wife Elizabeth, who had died within a year of her marriage with him, while he was still only crown prince. The third bride was sickly and unsympathetic, and from her Sigismund soon lost all hope of progeny, to his despair, for being the last male of the Jagiellos in the direct line, the dynasty was threatened with extinction. He sought to remedy the evil by liaisons with two of the most beautiful of his countrywomen, Barbara Gizanka and Anna Zajanczkowska, the diet undertaking to legitimatize and acknowledge as his successor any heir male who might be born to him; but their complacency was in vain, for the king died childless.
This matter of the king's marriage was of great political importance, the Protestants and the Catholics being equally interested in the issue. Had he not been so good a Catholic Sigismund might well have imitated the example of Henry VIII. By pleading that his detested third wife was the sister of his first and consequently the union was Uncanonical. The Polish Protestants hoped that he would take this course and thus bring about a breach with Rome at the very crisis of the confessional struggle in Poland, while the Habsburgs, who coveted the Polish throne, raised every obstacle to the childless kings remarriage. Not till Queen Catherine's death on, February 28, 1572, were Sigismund's hands free, but he followed her to the grave less than six months afterwards. Sigismund's reign was a period of internal turmoil and external expansion.
He saw the invasion of Poland by the Reformation, and the democratic upheaval which placed all political power in the hands of the szlcschta; he saw the collapse of the ancient order of the Knights of the Sword in the north (which led to the acquisition of Livonia by the republic) and the consolidation of the Turkish power in the south. Throughout this perilous transitional period Sigismunds was the hand which successfully steered the ship of state amidst all the whirlpools that constantly threatened to engulf it. A far less imposing figure than his father, the elegant and refined Sigismund II was nevertheless an even greater statesman than the stern and majestic [[Sigismund I].
Tenacity and patience, the characteristics of all the Jagiellos, he possessed in a high degree, and he added to them a supple dexterity and a diplomatic finesse which he may have inherited from his Italian mother. Certainly no other Polish king so thoroughly understood the nature of the ingredients of that witch's cauldron, the Polish diet, as he did. Both the Austrian ambassadors and the papal legates testify to the care with which he controlled this nation so difficult to lead. Everything went as he wished, they said, because he seemed to know everything beforehand. He managed to get more money than his father could ever get, and at one of his diets won the hearts of the whole assembly by unexpectedly appearing before them in the simple grey coat of a Masovian squire. Like his father, a pro-Austrian by conviction, he contrived even in this respect to carry the Polish nation, always so distrustful of the Germans, entirely along with him, thereby avoiding all serious complications with the ever dangerous Turk.
Only a statesman of genius could have mediated for twenty years, as he did, between the church and the schismatics without alienating the sympathies of either. But the most striking memorial of his greatness was the union of Lublin, which finally made of Poland and Lithuania one body politic, and put an end to the jealousies and discords of centuries. The merit of this crowning achievement belongs to Sigismund alone; but for him it would have been impossible. Sigismund II died at his beloved Knyszyne on July 6, 1572, at the age of 52.
Sigismund I the Old
List of Polish rulers
interregnum, later Henry III of France