hopes of reaching a negotiated peace quickly evaporated. Despite defeat in Bohemia, Frederick's allies included Georg Friedrich of Baden and Christian of Brunswick, while the Dutch provided him with military support after the Eighty Years War restarted in April 1621 and his father-in-law James funded an army of mercenaries under Mansfeld. However, their failure to co-ordinate effectively led to a series of defeats by Spanish and Catholic League forces, including Wimpfen in May 1622 and Höchst in June. By November 1622, the Imperialists controlled most of the Palatinate, apart from Frankenthal, which was held by a small English garrison under Sir Horace Vere. The remnants of Mansfeld's army took refuge in the Dutch Republic, as did Frederick, who spent most of his time in The Hague until his death in November 1632. At a meeting of the Imperial Diet in February 1623, Ferdinand forced through provisions transferring Frederick's titles, lands, and electoral vote to Maximilian. He did so with support from the Catholic League, despite strong opposition from Protestant members, as well as the Spanish. The Palatinate was clearly lost; in March, James instructed Vere to surrender Frankenthal, while Tilly's victory over Christian of Brunswick at Stadtlohn in August completed military operations. However, Spanish and Dutch involvement in the campaign was a significant step in internationalising the war, while Frederick's removal meant other Protestant princes began discussing armed resistance to preserve their own rights and territories. Danish intervention (1625–1629) With Saxony dominating the Upper Saxon Circle and Brandenburg the Lower, both kreise had remained neutral during the campaigns in Bohemia and the Palatinate. However, Frederick's deposition in 1623 meant John George of Saxony and the Calvinist George William, Elector of Brandenburg became concerned Ferdinand intended to reclaim formerly Catholic bishoprics currently held by Protestants. These fears seemed confirmed when Tilly restored the Roman Catholic Diocese of Halberstadt in early 1625. As Duke of Holstein, Christian IV was also a member of the Lower Saxon circle, while the Danish economy relied on the Baltic trade and tolls from traffic through the Øresund. In 1621, Hamburg accepted Danish 'supervision', while his son Frederick became joint-administrator of Lübeck, Bremen, and Verden; possession ensured Danish control of the Elbe and Weser rivers. Ferdinand had paid Albrecht von Wallenstein for his support against Frederick with estates confiscated from the Bohemian rebels, and now contracted with him to conquer the north on a similar basis. In