the Habsburg Emperor began in Cologne in 1636. These negotiations were initially blocked by Cardinal Richelieu of France, who insisted on the inclusion of all his allies, whether fully sovereign countries or states within the Holy Roman Empire. In Hamburg, Sweden, France, and the Holy Roman Empire negotiated a preliminary peace in December 1641. They declared that the preparations of Cologne and the Treaty of Hamburg were preliminaries of an overall peace agreement. The main peace negotiations took place in Westphalia, in the neighbouring cities of Münster and Osnabrück. Both cities were maintained as neutral and demilitarized zones for the negotiations. In Münster, negotiations took place between the Holy Roman Empire and France, as well as between the Dutch Republic and Spain who on 30 January 1648 signed a peace treaty ending the Eighty Years' War that was not part of the Peace of Westphalia. Münster had been, since its re-Catholicism in 1535, a strictly mono-denominational community. It housed the Chapter of the Prince-Bishopric of Münster. Only Roman Catholic worship was permitted, while Calvinism and Lutheranism were prohibited. Sweden preferred to negotiate with the Holy Roman Empire in Osnabrück, which was controlled by Protestant forces. Osnabrück was a bi-denominational Lutheran and Catholic city, with two Lutheran churches and two Catholic churches. The city council was exclusively Lutheran, and the burghers mostly so, but the city also housed the Catholic Chapter of the Prince-Bishopric of Osnabrück and had many other Catholic inhabitants. Osnabrück had been subjugated by troops of the Catholic League from 1628 to 1633 and was then taken by Lutheran Sweden. Delegations The peace negotiations had no exact beginning or end, because the 109 delegations never met in a plenary session. Instead, various delegations arrived between 1643 and 1646 and left between 1647 and 1649. The largest number of diplomats were present between January 1646 and July 1647. Delegations had been sent by 16 European states, 66 Imperial States representing the interests of 140 Imperial States, and 27 interest groups representing 38 groups. The French delegation was headed by Henri II d'Orléans, duc de Longueville and further comprised the diplomats Claude d'Avaux and Abel Servien. The Swedish delegation was headed by Count Johan Oxenstierna and was assisted by Baron Johan Adler Salvius. The Imperial delegation was headed by Count Maximilian von Trautmansdorff. His aides were: In Münster, Johann Ludwig von Nassau-Hadamar and Isaak Volmar. In Osnabrück, Johann Maximilian von