The Peace of Augsburg, also known as the Colony of Augsburg, was signed in September 1555 by Charles V, Holy Roman Emperor, and the Schmalkaldic League on 25 September 1555 in the imperial city of Augsburg. [4] He officially ended the religious war. It tried to build a religious colony in the vast German states. [5] The principle of cuius regio, eius religio, was the most important aspect of the treaty. This principle states that the ruler of the empire determined the faith of the people. [6] This was intended to ensure the internal unity of states within the Holy Roman Empire. If a leader was Catholic, he could determine that all those who lived in his empire must be Catholics. Those who did not accept the situation could emigrate to a Protestant jurisdiction. .