In 1499, Kiszka became regent of Smolensk and ordered improvements to Smolensk Kremlin. When the Muscovite–Lithuanian War resumed in 1500, Kiszka commanded a 500-men regiment in the Battle of Vedrosha. Lithuanians, commanded by Konstanty Ostrogski, suffered a great defeat and many Lithuanian nobles, including Kiszka's brother-in-law, were killed. Kiszka then devoted his attention to preparing Smolensk for a Russian assault. For his successful command of the defense during almost the three-month Siege of Smolensk in 1502 he was promoted to the Great Hetman (military commander). A six-year truce with Moscow was concluded in early 1503 and the Grand Duchy of Lithuania lost about a third of its territory.