While the third oldest brother, John I Albert was chosen by the Polish nobility (szlachta) to be the next king of Poland, the Lithuanians instead elected Alexander to be their next grand duke.

[6] Unable to successfully stop the incursions, Alexander sent a delegation to Moscow to make a peace settlement, which was signed in 1494 and ceded extensive land over to Ivan.

In an additional effort to instill a peace between the two countries, Alexander was betrothed to Helena, the daughter of Ivan III; they were married in Vilnius on 15 February 1495.

In the terms of this truce, which was concluded on 25 March 1503, Lithuania had to surrender about a third of its territory to the nascent expansionist Russian state; Alexander pledged not to touch lands including Moscow, Novgorod, Ryazan, and others, while a total of 19 cities were ceded.

Meanwhile, the liberality of Pope Julius II, who issued no fewer than 29 bulls in favor of Poland and granted Alexander Peter's Pence and other financial help, enabled him to restrain somewhat the arrogance of the Teutonic Order.