 Before deposing his brother Jaunutis in 1345, he ruled Kreva and, despite remaining pagan, married Maria, a daughter of the last prince of Vitebsk.After 1345 he became the Grand Duke of Lithuania and shared his power with his brother Kęstutis.Their successful collaboration is celebrated in Lithuanian historiography, and gave rise to a much debated theory that a tradition of co-rule or diarchy in Lithuania was customary and arose as early as 1285.