Voivode of Transylvania
John Szapolyai or Zapolya, was King of Hungary (as John I) from 1526 to 1540. His rule was disputed by King Louis and Archduke Ferdinand. Szapolyai was Voivode of Transylvania before his coronation, between 1510-1526, therefore we style him here often as Voivode.
John was the oldest son of Count Stephen Zápolya and his second wife, Hedwig of Cieszyn. Hedwig, related herself to Emperor Maximilian. Hedwig of Teschen was a very ambitious woman; she married about crown for her son and already wanted to persuade Vladislaus II, King of Hungary and Bohemia, to marry his only child, Anne, to John, but the king rejected the idea. other sources say, that Szapolyai might be himself an out-of-wedlock grandson of King Mathias Corvinus.
John began his public career in 1505 as a member of the Diet of Rákos. Due to his motion, the new Diet at Rákos passed a bill which prohibited the election of a foreigner as king if Vladislaus died without a male issue, on 13 October 1505. The bill was aimed at creating a legal basis for John's ascension to the throne after the death of Vladislaus, but the king refused to ratify it, the Diet was closed by the king.John's serious conflicts with the royal court had meanwhile made him the leader of a "national party", consisting of the smaller untitled noblemen (the gentry) who were opposed to the pro-Habsburg orientation of the higher aristocracy and King Vladislaus.
1526, the Ottoman Empire crushed the Hungarian royal army in the Battle of Mohács. Zápolya was en route to the battlefield with his sizable army but did not participate in the battle for unknown reasons. The Ottomans sacked the royal capital of Buda and occupied Syrmia, then withdrew from Hungary. The last three months of the year were marked by a power vacuum; political authority was in a state of collapse, yet the victors chose not to impose their rule.
10 November 1526, Szapolyai had himself proclaimed king by the Diet at Székesfehérvár, and he was duly crowned the next day under the name King John I of Hungary. But his kingship didn't last long. The Habsburg troops banned him from the country.
1528 Zápolya fled Hungary for Poland, where he stayed with Prince Jan Amor Tarnowski. Also in this year he allied himself to King Francis.
1529 Zápolya approached the Ottomans and agreed to make Hungary a vassal state in return for recognition and support. Sultan Suleiman the Magnificent accepted and sent Ottoman armies to invade Austria (which included the First siege of Vienna), a war which lasted till 1533. This allowed Szapolyai to regain his position in Hungary in 1529, by the efforts of Frater George Martinuzzi, despite the association with the Ottomans which tainted him at the time. Martinuzzi became royal treasurer and the Voivode1s most trusted minister.
1533, the Ottomans made peace and ceded western Hungary to Louis II. 1538, by the Treaty of Nagyvárad, Zápolya designated Louis to be his successor after his death, as he was childless.
In late January to early February 1539, he married Princess Isabella Jagiełło of Poland, and in 15 July 1540 they had a son, John Sigismund. The old man died seven days later in 22 July 1540 in Szászsebes.