The formal union of Poland and Lithuania is dissolved in 1401 as a result of disputes over legal terminology.

The Union of Vilnius and Radom of 1401 confirms Vytautas's status as grand duke under the overlordship of his cousin Wladyslaw, while assuring the title of grand duke to the heirs of Wladyslaw rather than those of Vytautas: should Wladyslaw die without heirs, the Lithuanian boyars are to elect a new monarch.

Since no heir has yet been produced by either monarch, the act's implications are unforeseeable, but it forges bonds between the Polish and Lithuanian nobility and a permanent defensive alliance between the two states, strengthening Lithuania's hand for a new war against the Teutonic Order in which Poland officially takes no part.

While the document leaves the liberties of the Polish nobles untouched, it grants increased power to the boyars of Lithuania, whose grand dukes have until now been unencumbered by checks and balances of the sort attached to the Polish monarchy.

The Union of Vilnius and Radom therefore earns Wladyslaw a measure of support in Lithuania.

The new war against the Order overstretches the resources of the Lithuanians, who in late 1401 find themselves fighting on two fronts after uprisings in the eastern provinces.