The death of his older brother Nicholas made him his father's heir. Bolko III died in 1410 and was succeeded by John. Like his father, he didn't need a regent, since he was an adult at the time. John nominally co-ruled with his younger brotherHenry II, but he retained all the government in his hands. Henry II died childless in 1420 and since then John ruled over Münsterberg alone. Like his father and grandfather, he remained a faithful vassal of the House of Luxembourg. During the first years of his rule the Polish–Lithuanian–Teutonic War took place. He participated there at the side of the Teutonic Order; however, his interference in the war was limited, especially after the Battle of Tuchola, where he escaped from the battlefield with other noble and Teutonic knights. On 6 January 1420 John was present in the Reichstag of Breslau, where he spent a major disincentive to the Polish sentence in the process against the Teutonic Order. The previous politics of his predecessors was negligible, so when John assumed the government over his Duchy, he only had the town of Münsterberg. For this reasons, he married around 19 March 1408 with Elizabeth, widow of the powerful Polish magnateSpytek II of Melsztyn and daughter of Emeric I Lackfi, General Starost of Ruthenia, Ban of Dalmatia and of Hungary. Thanks to this union, John obtain a huge dowry and the needed financial autonomy. The case was more strange by the fact that Elisabeth's first husband was one of the most closest advisers of King Władysław II Jogaila of Poland, the long-time enemy of John's sovereign, the Sigismund of Luxembourg, King of Hungary and Germany. Moreover, despite the hostile politics of King Sigismund, Elizabeth successfully continued with his many Polish contacts, even after his remarriage with the Duke of Münsterberg. The union proved to be childless, so John was the last male representative of Münsterberg branch of the Piast dynasty. By 1428 Silesia was in the middle of the Hussite Wars. Initially, seeing no chances of victory, Duke Louis II of Brieg entered into an arrangement with John, under which he was compelled to not interfere with the movements of enemy troops. However, for unknown reasons, John broke the ceasefire, and with this he began his participation in the war. John died on 27 August 1428 in the battle of Altwilmsdorf, in the Valley of Glatz, fighting against the Hussite leader Jan Kralovca. The cause of the disaster was a thoughtless attack of the Hussite troops, or earthwork built wagons from the battle. It's unknown where John was buried. On the alleged place of the Duke's death was built a Chapel during 1904–1905 designed by Ludwig Schneider. After his death, and according to the treaty of 1343, the Duchy of Münsterberg was annexed by the Kingdom of Bohemia.
