In 1700, with his father and uncle, he took part in the Battle of Olkieniki, but he was forced to flee when the Lithuanian nobility, who had allied themselves against the Sapieha family, gained the upper hand.
During the Great Northern War (1700-1721), Sapieha chose the side of Charles XII of Sweden and supported his protégé, Stanislaus Leszczynski, who was elected King of Poland on 12 July 1704.
In 1709, Charles XII was defeated by Peter I of Russia at Poltava.
Stanislaus Leszczynski was ousted from the Polish throne and Sapieha lost all his political functions.
Aleksander Paweł Sapieha died in Vilnius on 4 January 1734.
Sources
Anatoly Gritskevich, Sapieha // Grand Duchy of Lithuania: Encyclopedia. In 3 vols. Vol. 2: Cadet Corps – Yatskevich / Ed.: G. P. Pashkov (Gal.ed.) and others; Artist Z. E. Gerasimovich. – Mn.: BelEn, 2006. −792 p.: ill. p. 549. ISBN 985-11-0315-2, ISBN 985-11-0378-0 (vol. 2) (In Russian)