He supported a political union with
Muscovy in 1584–1600 and led the
diplomatic mission to Moscow in 1600 that proposed the union to
tzar Boris Godunov, who declined the proposal. He also participated in
wars with Muscovy under rule of
Stephen Báthory and King of Poland and Grand Duke of Lithuania
Sigismund III Vasa. He became an adviser of Sigismund III and supported his radical plans to take over the Muscovite throne and reclaim
Smolensk by force. He participated in establishing the
Lithuanian Tribunal in 1578. As Chancellor he was the main editor and publisher of the last version of the
Statute of the Grand Duchy of Lithuania. He laid grounds for the establishment of the Law Faculty in the
University of Vilnius, which was created in 1641. He was co-initiator and a participant in the military expedition to Moscow in 1618 by King of Poland and Grand Duke of Lithuania
Władysław IV. As
Sejm Marshal, he led the ordinary
Sejm in
Warsaw from 4 October to 25 November 1582. He was a benefactor of many catholic churches in the Grand Duchy. He established the long-term power and wealth of the
Sapieha family. Sapieha died on 1633 and was interred in the cellars of the
Church of St. Michael the Archangel in Vilnius, which he himself commissioned. His tomb remains there to the present day and is still the largest piece of art of its kind in the territory of Lithuania. == Gallery ==