discarded by modern scholarship. Johann Sylvan, Adam Neuser, Johannes Willing, Thomas Erastus, Michael Diller, Johannes Brunner, Tilemann Mumius, Petrus Macheropoeus, Johannes Eisenmenger, Immanuel Tremellius and Pierre Boquin are all likely to have contributed to the Catechism in some way. Frederick himself wrote the preface to the Catechism and closely oversaw its composition and publication. Frederick, who was officially Lutheran but had strong Reformed leanings, wanted to even out the religious situation of his highly Lutheran territory within the primarily Catholic Holy Roman Empire. The Council of Trent had just concluded with its conclusions and decrees against the Protestant faiths, and the Peace of Augsburg had only granted toleration for Lutheranism within the empire where the ruler was Lutheran. One of the aims of the catechism was to counteract the teachings of the Roman Catholic Church as well as Anabaptists and "strict" Gnesio-Lutherans like Tilemann Heshusius and Matthias Flacius, who were resisting Frederick's Reformed influences, particularly on the matter of Eucharist (the Lord's Supper). The Catechism-based each of its statements on biblical proof-texts, and Frederick himself would defend it as biblical, not reformed, at the 1566 Diet of Augsburg when he was called to answer to charges of violating the Peace of Augsburg. This was the Heidelberg Catechism, officially called the ″Catechism, or Christian Instruction, according to the Usages of the Churches and Schools of the Electoral Palatinate.″ In November 1619, the Royal Crown of Bohemia was offered to the Elector, Frederick V. (He was married to Princess Elizabeth, eldest daughter of James VI and I of Scotland and England, respectively.) Frederick became known as the "Winter King", as he reigned for only one winter before the Imperial House of Habsburg regained Bohemia by force. His overthrow in 1621 marked the beginning of the Thirty Years' War. In 1622, after a siege of two months, the armies of the Catholic League, commanded by Johann Tserclaes, Count of Tilly, captured the town. Tilly gave the famous Bibliotheca Palatina from the Church of the Holy Spirit to the Pope as a present. The Catholic and Bavarian House of Wittelsbach gained control over the Palatinate and the title of Prince-Elector. In late 1634, after the Swedish army had conquered Heidelberg, imperial forces attempted to recapture the city. They quickly took the city, but were unable to take the castle. As they prepared to blow up its fortifications with gunpowder the French army arrived, 30,000