In the second half of his reign, Casimir IV’s intention was to weave a network of alliances based on the several branches of the Jagiellonian dynasty. In spite of the possibilities then opening up, he did not seek further restitution of Silesian lands to the Polish crown; rather he devoted every effort to place his sons born of Elizabeth of Austria (the daughter of Emperor Albert II) on the thrones of Bohemia, Hungary, Poland and Lithuania. In this he was successful.
In Bohemian affairs Casimir IV did not allow himself to be drawn into the Catholic coalition against King George of Podebrady; rather, he attempted to mediate between him, the emperor and King Matyas Corvinus of Hungary. George agreed to recognise Casimir’s eldest son, Vladislav, as his heir to the Bohemian throne. After George’s death, the Bohemian Diet duly elected Vladislav in 1471, although Matyas Corvinus managed to establish himself in Silesia, Lusatia and Moravia. The conflict with the king of Hungary found its expression in military and diplomatic disputes. Matyas’s death in 1490 opened the way for Vladislav to mount the Hungarian throne; with the aid of Hungarian magnates, he supplanted his younger brother, Jan Olbracht, the favourite of the gentry, who was compensated for his loss with the governorship of Silesia.
Thus the Jagiellonian dynasty took control of a vast expanse of central and eastern Europe from the borders with Moscow and the Baltic to the Black Sea and the Adriatic coastlands. Yet Casimir IV’s diplomatic successes aroused no enthusiasm in Poland or Lithuania, since they brought no immediate advantages. The Habsburgs were to gather in the fruit of the king’s labour in the following generation. The authority that Casimir IV created through the successes of the first decades of his reign was undermined by the onerous and, in noble eyes, unsuccessful military campaigns fought for dynastic interests. Important problems concerning the reform of the military and fiscal systems remained unsolved.
Casimir IV rarely visited Lithuania, but he did not yield to the demands of the Lithuanian nobles for the establishment of a lieutenancy there. At that time there was a growth in the expansion of Moscow which snatched Novgorod from the Lithuanian sphere of influence (1471) and followed a policy of gathering Rus'ian lands under its control at the expense of Lithuania. Casimir IV spent four years in Lithuania, entrusting the government of the kingdom to his second son, Casimir (later canonised), for two years. The king survived an attempt made on his life by Rus'ian princes with the connivance of the grand duke’s vassals, two of whom were sentenced by the grand-ducal council and beheaded. The counter-offensive against Moscow, which had captured several border duchies and inspired Tatar invasions of the southern regions, was unsuccessful.
In 1475 the Turks took over the Genoese colony of Kaffa, on the northern coast of the Black Sea, a major centre of oriental trade, and in 1484 they seized Kilia (at the mouth of the Danube) and Akkerman (at the mouth of the Dnestr), which belonged to Moldavia. In this situation Stephen, prince (voivode) of Moldavia, renewed his allegiance to the Polish crown, following the example of his predecessors. The immediate threat from the Turks and the Tatars was henceforth to become a constant feature of Lithuanian and Polish foreign policy.