During all the wars with the Turks, a Transylvanian count, John of Tapoli, was disputing Ferdinand’s right to the throne of Hungary and claiming it for himself.  He even entered into negotiations with the Turks, and cooeperated with Solyman in his invasion of Hungary, having the promise of the sultan that he should be appointed king of the realm as soon as it was brought in subjection to Turkey.  The Turks had now possession of Hungary, and the sultan invested John of Tapoli with the sovereignty of the kingdom, in the presence of a brilliant assemblage of the officers of his army and of the Hungarian nobles.

The last discomfiture and retreat of Solyman encouraged Ferdinand to redoubled exertions to reconquer Hungary from the combined forces of the Turks and his Transylvanian rival.  Several years passed away in desultory, indecisive warfare, while John held his throne as tributary king to the sultan.  At last Ferdinand, finding that he could not resist their united strength, and John becoming annoyed by the exactions of his Turkish master, they agreed to a compromise, by which John, who was aged, childless and infirm, was to remain king of all that part of Hungary which he held until he died; and the whole kingdom was then to revert to Ferdinand and his heirs—­But it was agreed that should John marry and have a son, that son should be viceroy, or, as the title then was, univode, of his father’s hereditary domain of Transylvania, having no control over any portion of Hungary proper.

Somewhat to the disappointment of Ferdinand, the old monarch immediately married a young bride.  A son was born to them, and in fourteen days after his birth the father died of a stroke of apoplexy.  The child was entitled to the viceroyship of Transylvania, while all the rest of Hungary was to pass unincumbered to Ferdinand.  But Isabella, the ambitious young mother, who had married the decrepit monarch that she might enjoy wealth and station, had no intention that her babe should be less of a king than his father was.  She was the daughter of Sigismond, King of Poland, and relying upon the support of her regal father she claimed the crown of Hungary for her boy, in defiance of the solemn compact.  In that age of chivalry a young and beautiful woman could easily find defenders whatever might be her claims.  Isabella soon rallied around her banner many Hungarian nobles, and a large number of adventurous knights from Poland.

Under her influence a large party of nobles met, chose the babe their king, and crowned him, under the name of Stephen, with a great display of military and religious pomp.  They then conveyed him and his mother to the strong castle of Buda and dispatched an embassy to the sultan at Constantinople, avowing homage to him, as their feudal lord, and imploring his immediate and vigorous support.