The prince-bishopric was a sovereign member of the Holy Roman Empire (formally from 6 Nov 1225) and part of the Livonian Confederation until its dissolution in 1561.

The Estonian Diocese was established by the Bishop of Riga in 1211 and its first nominal seat was Leal (Lihula) in western Estonia.

In 1242, Bishop Hermann with his Ugaunian subjects was defeated by Novgorod's prince Alexander Nevsky in the famous Battle on Lake Peipus.

He was the archenemy of the Livonian Order and made a coalition against it with Lithuania, Mecklenburg, and the Victual Brothers (notorious pirates of the Baltic Sea).

Ivan insisted that the Dorpat was the ancient Russian fortress of Yuryev (referring to the short-lived Rus' rule of the area after its conquest by Yaroslav I the Wise, 1030–61(?)).

The rulers of Dorpat tried to negotiate a smaller amount in the interest of extending the truce, but Ivan dismissed the diplomats and started the war.