Algirdas occupied the important principalities of Smolensk and Bryansk in western Moscow principality. Although his relationship with the grand dukes of Moscow principality was generally friendly (demonstrated by his marriages to two Orthodox Russian princesses), he besieged Moscow in 1368 and 1370 during the Lithuanian–Muscovite War (1368–1372). An important feat by Algirdas was his victory over the Tatars in the Battle of Blue Waters at the Southern Bug in 1362, which resulted in the breakup of the Kipchaks and compelled the khan to establish his headquarters in the Crimea.