increased pressure grew on Spanish minister Olivares to make peace, especially after attempts to hire Polish auxiliaries proved unsuccessful. Cutting the Spanish Road forced Madrid to resupply their armies in Flanders by sea and in October 1639 a large Spanish convoy was destroyed at the Battle of the Downs by a Dutch fleet, led by Maarten Tromp. Elsewhere, Dutch attacks on Portuguese colonies caused unrest in Portugal, then part of the Spanish Empire. Combined with heavy taxes, in 1640 this caused revolts first in Portugal, then Catalonia. After the French captured Arras in August 1640 and overran Artois, Olivares argued Spain should accept Dutch independence and focus on retaining Flanders. At the same time, the Dutch peace party had been strengthened in 1637 when Frederick Henry recaptured Breda. Convinced the war was won and the only question was the price of peace, in 1640 the regenten who dominated Dutch politics reduced the army budget, despite objections from Frederick Henry. After Bernard died in July 1639, his troops joined Banér's Swedish army on an ineffectual campaign along the Weser, the highlight being a surprise attack in January 1641 on the Imperial Diet in Regensburg. Forced to retreat, Banér reached Halberstadt in May where he died, and despite beating off an Imperial force at Wolfenbüttel in June, his largely German troops mutinied due to lack of pay. The situation was saved by the arrival of Lennart Torstenson in November with 7,000 Swedish recruits and enough cash to satisfy the mutineers. French victory at Kempen in January 1642 was followed by Second Breitenfeld in October 1642, where Torstenson inflicted almost 10,000 casualties on an Imperial army led by Archduke Leopold Wilhelm of Austria. The capture of Leipzig in December gave the Swedes a significant new base in Germany, and despite their failure to take Freiberg, by 1643 the Saxon army had been reduced to a few isolated garrisons. While Ferdinand accepted a military solution was no longer possible, by fighting on he hoped to prevent the Imperial Estates joining his peace negotiations with France and Sweden, thus preserving his authority by allowing him to represent the Empire as a whole. This seemed more likely when Richelieu died in December 1642, followed by Louis XIII in May 1643, leaving his five-year-old son Louis XIV as king. However, Richelieu's policies were continued by his successor Cardinal Mazarin, while French gains in Alsace allowed him to