From the longer Wikipedia page 
Hans von Baysen or Jan Bażyński (c. 1394 – 1459) was a Prussian knight and statesman, leader of the Prussian Confederation and the first Polish governor of Royal Prussia
He was a leader of the gathering of Prussian nobility in 1435 which was dissatisfied with the rule of the Teutonic Knights. He was also a member of the Lizard Union, an organization of Prussian nobles and knights who sought the incorporation of Prussia into the Kingdom of Poland. As the Standard-bearer of Ostróda (Osterode) he took part in the founding of the Prussian Confederation, and was one of the signatories of the founding document of the Confederation on March 14, 1440 in Kwidzyn (Marienwerder). He was a member of the Secret Committee of the Confederation and took a public stance against attacks made against the organization by the Papal legate and the new Grand Master of the Order.
He was the head of the delegation which came from Toruń (Thorn) to Kraków in February 1454, which asked the King of Poland Casimir IV Jagiellon to reincorporate Prussian lands into the Polish kingdom. Consequently he led the uprising of the Prussian Estates against the Knights. In 1454, during the Thirteen Years' War, in which the cities of the Prussian Confederation financed Polish military expenses, he was made governor of Royal Prussia by the King of Poland, which after the war became a part of the Polish-Lithuanian Commonwealth. As the governor his residence was in Elbląg. In 1457 and 1459 he commanded the defense of Malbork against attacks by the Teutonic Knights, who also unsuccessfully tried to assassinate him. In 1454 he was made the starosta of Sztum (Shtum) and in 1456 of Tolkmicko (Tolkemikt).
He died at Marienburg Castle (Malbork Castle) and was buried at Elbląg. He was succeeded as governor of Royal Prussia by his brother Ścibor Bażyński (Tiburcius/Stibor von Baysen).