Duchy of Saint Sava

Duchy of Saint Sava (Ducatus Sancti Sabae, Bosnian and Voјvodstvo Svete Save, војводство Светог Саве    ) was a late medieval statelet which existed amid the Ottoman conquest of the Balkans. It was ruled by Stjepan Vukčić and his son Vladislav, of the Kosača noble family, and included parts of modern day Bosnia & Herzegovina, Croatia, Montenegro and Serbia.

Stjepan titled himself "Vojvoda of Saint Sava", after the first Serbian Archbishop, Saint Sava. Vojvoda in German translation is Herzog ("duke"), and this would later give the name to the present-day region of Herzegovina, as the Ottomans used Hersek Sancağı ("Sanjak of the Herzog") for the province which was transformed into an Ottoman sanjak.

History
In a document sent to Holy Roman Emperor Frederick III on 20 January 1448, Stephen Vukčić Kosača styled himself "Vojvoda (duke, herzog) of Saint Sava" (Vojvoda svetog Save), "lord of Hum and Primorje" (gospodar Humski i Primorski), and "Grand Duke", and forced the Bosnian kingdom to recognize him as such. The title "Vojvoda of Saint Sava" had considerable public relations value, because Sava's relics, which were located in Mileševa, were consider miracle-working by people of all Christian faiths in the region.

On 15 February 1444, Stephen signed a treaty with Alfonso V, King of Aragon and Naples, becoming his vassal in exchange for the king's help against Stjepan's enemies, namely King Stephen Thomas of Bosnia, Duke Ivaniš Pavlović and the Republic of Venice. In the same treaty Stjepan promised to pay regular tribute to Alfonso instead of his tribute to the Ottoman sultan, which he had done up until then.

Stjepan Vukčić died in 1466, and was succeeded by his eldest son Vladislav Hercegović. In 1482 he was overpowered by Ottoman forces led by Stjepan Vukčić's youngest son, Hersekli Ahmed Pasha, who converted to Islam prior to that. In the Ottoman Empire, Herzegovina was organized as a province (sanjak) within the state (pashaluk) of Bosnia.

Stjepan founded the Serbian Orthodox Zagrađe Monastery near his realm's seat in Herceg Novi, modern-day Montenegro, and the Savina Monastery, also near Herceg Novi.

Rulers

 * Stjepan Vukčić Kosača, 1435–1466
 * Vladislav Hercegović, 1466–1483