The Second Schmalkaldic War was fought between the Catholic Habsburg-ruled Holy Roman Empire and the Protestant Schmalkaldic League in 1552. After Emperor Charles V ordered several German Lutheran princes to revert to Catholicism, they once again revolted and, with French help, emerged victorious, forcing the Emperor to allow for each prince to decide the religion of his realm in the 1555 Peace of Augsburg.
Background[]
At the 1548 Diet of Augsburg, Emperor Charles V ordered Protestants to readopt traditional Catholic beliefs and practices like the Seven Sacraments, while allowing Protestant clergymen the right to marry. A follow-up Leipzig Interim put forth by Duke Maurice of Saxony and Philip Melanchthon attempted to reach a compromise under which Lutherans could retain their core thought beliefs while yielding on matters like church rituals. Seeing that compromise with his previous Habsburg allies was a failure, Maurice decided to drive Charles V and his Imperial army away from Saxony. On 22 May 1551, John Albert I of Mecklenburg, Albert of Prussia, William IV of Hesse-Kassel, and Albert Alcibiades of Brandenburg-Kulmbach allied to defend the freedom of the Imperial princes and liberate the imprisoned Philip I of Hesse. The Protestant princes allied with King Henry II of France, who initiated the Italian War of 1551-1559 and, on 15 January 1552, promised financial and military aid to the German princes in exchange for the cession of Metz, Verdun, and Toul to France.
War[]
Maurice and a Saxon army were ordered by Charles V to suppress the revolt of Magdeburg, which refused to obey the Augsburg Interim, only for Maurice to ally with Magdeburg. The allied princes conquered the southern German cities loyal to the Emperor and invaded Tyrol as the French occupied the west bank of the Upper Rhine. The Emperor barely escaped Innsbruck and fled to Villach to rally new troops as his brother Ferdinand of Austria negotiated with Maurice and the other Protestant princes. In August 1552, the Peace of Passau saw the German princes abandon their alliance with France in exchange for the Imperials' release of their prisoners, and the 1555 Peace of Augsburg saw the Holy Roman Empire allow its princes to adopt either Catholicism or Lutheranism as their state religions (though not Calvinism).