 Mikalojus had been a regent of Smolensk from 2 December 1481; in 1483 a 10,000-strong army was summoned by him for protection of Smolensk lands.He had been the Castellan of Trakai since 31 May 1488 and regent of Novgorodok, later a regent of Bielsk Podlaski.He was the Voivod of Vilnius since 1492 and the first Grand Chancellor of Lithuania from 1504 until his death in 1509.