| Native Name: | Księstwo wieluńskie (Polish) Ducatus Velumensis (Latin) |
| Conventional Long Name: | Duchy of Wieluń |
| Era: | High Middle Ages |
| Status: | Fiefdom of Kingdom of Poland |
| Government Type: | District principality |
| Life Span: | 1370–1391 |
| Event Start: | Partition from Kingdom of Poland |
| Date Start: | 17 November |
| Year Start: | 1370 |
| Event End: | Incorporation into Kingdom of Poland |
| Date End: | 1391 |
| P1: | Kingdom of Poland (1025–1385)Kingdom of Poland |
| Flag P1: | Flag of the Kingdom of Poland.svg |
| Border P1: | no |
| S1: | Kingdom of Poland (1385–1569)Kingdom of Poland |
| Flag S1: | Flag of the Kingdom of Poland.svg |
| Border S1: | no |
| Religion: | Roman Catholic |
| Coat Alt: | Coat of arms Wieluń Land in 1410 |
| Image Map Caption: | Map of the duchy |
| Currency: | Wieluń denar |
| Capital: | Wieluń |
| Official Languages: | Polish, Latin |
| Title Leader: | Duke |
| Leader1: | Vladislaus II of Opole |
| Year Leader1: | 1370–1391 |
Duchy of Wieluń was a district principality and a fiefdom within the Kingdom of Poland. It was formed in 1370 from part of the Kingdom of Poland, and existed until 1391 when it was incorporated back into it. The country was located in Wieluń Land with Wieluń as its capital. Its only ruler was Vladislaus II of Opole of Silesian Piast dynasty.
The state was formed on 17 November 1370, when King of Poland, Louis I of Hungary, had given Vladislaus II of Opole territory of Wieluń Land as his own duchy. Vladislaus II was given those lands due to his help to the king in the process of legal succession of the throne of Poland.[1] The state located in Wieluń Land with Wieluń as its capital. Local mint had begun minting new silver coins known as Wieluń denars.[2] [3]
In the spring of 1376, Vladislaus II had sent his knights to join forces led by Sędziwój Pałuka against Władysław the White in his rebellion against the Polish king.[1]
In 1378, the duchy was enlarged with the incorporation of Bobolice, Brzeźnica, Krzepice and Olsztyn. Around that time, the state was subdivided into districts of Wieluń, Ostrzeszów, Olsztyn, Krzepice, Brzeźnica and Bolesławiec.[4]
Between 13 July and 15 August 1391, while Vladislaus II was in Hungary, forces aligned with Władysław II Jagiełło had besieged Kruszwica Castle and later had taken the stronghold in Racibórz, both of which belonged to Vladislaus. By doing so, they had started the war between two monarchs. In September 1391, Jagiełło's forces had captured lands of Gniewkowo Land and Dobrzyń. On 15 September 1391, Jagiełło's forces had entered Wieluń, beginning the war theatre on the territories of the duchy. In the autumn of 1391, the war had ended with Jagiełło's victory. Following that, Duchy of Wieluń was incorporated into Kingdom of Poland.[1] [5] [6]
From around 1378, the duchy was subdivided into districts of Wieluń, Ostrzeszów, Olsztyn, Krzepice, Brzeźnica and Bolesławiec.[4]