jogaila left his brother skirgaila as regent in lithuania. however, skirgaila was unpopular with the people and vytautas saw an opportunity to become grand duke. in 1389, he attacked vilnius but failed. in early 1390, vytautas again allied with the teutonic order. vytautas had to confirm his agreement of 1384, and cede samogitia to the order. his army now invaded lithuania. also, to gain more influence, vytautas married his only daughter sophia to vasili i of russia in 1391.