 By the mid-14th century, an expanding Lithuania had absorbed Chernigov and Severia.Algirdas, the successor of Gediminas, forged an alliance with the Grand Duchy of Tver and undertook three expeditions against Moscow, attempting to take advantage of the youth of the Grand Prince of Moscow, Dmitry Ivanovich, who nevertheless succeeded in fending off these encroachments.The first intrusions of Lithuanian troops into the Moscow principality occurred in 1363.