The Augsburg Confession is the primary confession of faith of the Lutheran Church and one of the most important documents of the Lutheran Reformation. The Augsburg Confession was written in both German and Latin and was presented by a number of German rulers and free-cities at the Diet of Augsburg on 25 June 1530. The Holy Roman Emperor Charles V had called on the Princes and Free Territories in Germany to explain their religious convictions in an attempt to restore religious and political unity in the Holy Roman Empire and rally support against the Turkish invasion. It is the fourth document contained in the Lutheran Book of Concord.