During the period of Northern Crusades in the beginning of the 13th century the fort of "Tarbatu" (or "Tharbata", Tartu) was captured by the crusading Livonian Knights — also known as the Brothers of the Sword (German: "Schwertbrüder") — and recaptured by Estonians on several occasions. In 1224, after Ugaunia had recognized the supremacy of Novgorod and Pskov princes who sent additional troops led by prince Vyachko of Kukenois to the fort, it was besieged and conquered for one last time by the German crusaders. Subsequently, known as Dorpat (Latin: "Tarbatum"), Tartu became a commercial centre of considerable importance during the later Middle Ages and the capital of the semi-independent Bishopric of Dorpat.