reform it needed peace. The destruction of the United Provinces of the Netherlands was necessary. Dutch colonial policy tried to undermine Spanish and Portuguese hegemony. Spinola and the Spanish army were focused on the Netherlands, and the war seemed to be going in Spain's favor. In 1627, the Castilian economy collapsed. The Spanish had been debasing their currency to pay for the war and prices exploded in Spain just as they had in previous years in Austria. Until 1631, parts of Castile operated on a barter economy as a result of the currency crisis, and the government was unable to collect any meaningful taxes from the peasantry, depending instead on its colonies (via the Spanish treasure fleet). The Spanish armies in Germany resorted to "paying themselves" on the land. Olivares, who had backed certain tax measures in Spain pending the completion of the war, was further blamed for a fruitless war in Italy, the War of the Mantuan Succession. The Dutch, who during the Twelve Years' Truce had made their navy a priority, proceeded to plunder Spanish and (especially) Portuguese maritime trade, on which Spain was wholly dependent after the economic collapse. Spanish victories in Germany and Italy were not enough to matter, and their navy began suffering losses. In 1630, Gustavus Adolphus of Sweden landed in Germany and relieved the port of Stralsund that was the last stronghold on the continent held by German forces belligerent to the Emperor. Gustav then marched south winning notable victories at Breitenfeld and Lutzen, attracting greater support for the Protestant cause the further he went. The situation for the Catholics improved with Gustav's death at Lutzen in 1632 and a shocking victory for Imperial forces under Cardinal-Infante Ferdinand and Ferdinand II of Hungary at Nordlingen in 1634. From a position of strength, the Emperor approached the war-weary German states with a peace in 1635; many accepted, including the two most powerful, Brandenburg and Saxony. Cardinal Richelieu had been a strong supporter of the Dutch and Protestants since the beginning of the war, sending funds and equipment in an attempt to stem Habsburg strength in Europe. Richelieu decided that the recently signed Peace of Prague was contrary to French interests and declared war on the Holy Roman Emperor and Spain within months of the peace being signed. The more experienced Spanish forces scored initial successes; Olivares ordered a lightning campaign into northern France from