On this day in 1539 Charles V and Protestants signed the Treaty of Frankfurt.
The Treaty of Frankfurt (also spelled Treaty of Frankfort), also known as the Truce of Frankfurt, was a formal agreement of peace between Charles V, Holy Roman Emperor and Protestants on 19 April 1539.
The parties met at Frankfurt-on-the-Main and the Lutherans were represented by Philip Melancthon.
The treaty stated that the emperor would not take any violent actions against the Protestants, who had formed an alliance known as the Schmalkaldic League, for fifteen months starting 1st May during this time both parties could try and resolve the differences in their confessions.
As a result of this peace, the Schmalkaldic League lost the protection of France.