[3] He was a strong supporter of Grand Duke Vytautas the Great, who awarded the loyal ally with the seat of Elder of Samogitia as Mykolas' mother was of Samogitian descent.
[4] Mykolas presided over Christianization of Samogitia in 1413, subdued a peasant rebellion in 1418,[2] and foiled a plot by nobles against Vytautas in 1419.
[4] In 1430, after the death of Vytautas, Mykolas Kęsgaila and his brothers Rumbaudas and Jaunius Valimantaitis supported the accession of Švitrigaila to the Lithuanian throne.
[5] Possibly, such an outcome was influenced by Mykolas' daughter, the wife of Sigismund's influential ally Jonas Goštautas.
[2] According to the Bychowiec Chronicle, after the murder of Sigismund in 1440, Mykolas was among supporters of Casimir IV Jagiellon for the throne of Grand Duke.