Background
Jakob was born in 1413 in Sienno, the son of Dobisław of Oleśnicy a local aristocrat of the Debno family and his wife Catherine Oleśnicka, daughter of Dymitr of Goraj. His father, Dobiesława Olesnica mala Dębno, was Count of Sandomierz.
Jakob was born in 1413 in Sienno, the son of Dobisław of Oleśnicy a local aristocrat of the Debno family and his wife Catherine Oleśnicka, daughter of Dymitr of Goraj. His father, Dobiesława Olesnica mala Dębno, was Count of Sandomierz.
He studied law and Theology in Rome and from 1435 was a Canon of Krakow Cathedral.
He was also a 15th century diplomat for the Polish Crown. John of Sienna Castellan of Lwów
Dymitr of Sienna (d 1465) Canon of Krakow
Nicholas of Sienna (d 1484) Archdeacon of Sandomierz
Paul of Sienna (c 1410-1444) the Royal Secretary
Andrzej Sienieński (d 1494) Chamberlain of Sandomierz
He was also a nephew of Cardinal Oleśnicki. As a diplomat he served as Secretary of KingVladislav Varnenchik and King Casimir IV Jagiellon.
As a diplomat he was sent on missions to Hungary in 1442 and 1448 and in 1459 he represented the King at the Congress of Mantua.
He was sent on a diplomatic missions in 1442 to Hungary, in 1448AD to Rome. In 1459 he represented the King at the Congress in Mantua.
November 24, 1460,
Pope Pius II appointed him Bishop of KrakóWest Unfortunately, the King had other plans and request the appointment of John Gruszczynski, consecrated on May 31, 1461.
The conflict escalated with the Pope (Pius II) on 2 June 1461, threatening to excommunicate the King.
The King then banished Jakub. Eventually on 16 January 1462 the conflict was resolved through intersession of the papal legate Jerome Lando, Archbishop of Crete. In January 1463 at the Sejm in Piotrków the Kings appointee abdicated the bishopric of KrakóWest
Pope Pius II compsensated Jakob and he received the bishopric of Włocławek.
In Wloclawek and in Gniezno he installed oak pew stalls and rich liturgical equipment, and donated to the library of Krakow Academy. He was a signatory to the Acting of peace of 1466.
He died 4 October 1480 in Łowicz and was buried in the Cathedral of Gniezno. He erected the cross on the Cathedral, still there today.