Sigismund was intermittently at war with Vasili III of Muscovy beginning in 1507, before the Polish army was fully under his command. Further tensions escalated when Vasili also discovered that Sigismund was bribing Khan Meñli I Giray to attack the Grand Duchy of Moscow. In December 1512, Muscovite forces marched into the Grand Duchy of Lithuania seeking to capture Smolensk, a major trading center between Russia and Europe. The initial six- and four-week sieges in 1513 were a failure, but the city fell to the Muscovites in July 1514.