 Mykolas, son of Valimantas, was first mentioned in the Pact of Vilnius and Radom of 1401.He was a strong supporter of Grand Duke Vytautas, who awarded the loyal ally with the seat of Elder of Samogitia as Mykolas' mother was of Samogitian stock.Mykolas presided over Christianization of Samogitia in 1413, subdued a peasant rebellion in 1418, and foiled a plot by nobles against Vytautas in 1419.