King Vladislav's relations with the emperor deteriorated when in 1172 he abdicated in favour of Frederick,[2] trying to implement a line of succession in accordance to the principle of agnatic seniority, but without consulting Barbarossa.

While the Prague throne was claimed by Vladislav's cousins, sons of the late Duke Soběslav I, Frederick was unable to hold on to his duchy, as his tenancy was approved by neither the Bohemian diet nor the emperor.

While Soběslav ignored a summons to appear at the Imperial court, Frederick was able to forge an alliance with the Moravian prince Conrad III Otto of Znojmo and the Babenberg duke Leopold V of Austria.

First attacked and defeated by Soběslav's forces at the Battle of Loděnice, he finally prevailed in a decisive victory outside the Prague city walls, in the area of present-day Nové Město, on 27 January 1179.

However, his reign remained overshadowed by the internal struggles of the Přemyslid dynasty: when he tried to assert the rule of his younger half-brother Ottokar over Moravia, his former ally Prince Conrad of Znojmo turned against him and temporarily drove him out of Prague.

When Margrave Conrad was defeated by the forces of Frederick's half brother Ottokar in a bloody battle at Loděnice, the Bohemian and Moravian Přemyslids finally met at Knín in 1186.