 Defeat at Nördlingen in September 1634 forced the Swedes to retreat, while most of their German allies made peace with Ferdinand in the 1635 Treaty of Prague.The other major European conflict of the period was the 1568 to 1648 Eighty Years' War between Spain and the Dutch Republic, suspended in 1609 by the Twelve Years' Truce.The Spanish strongly objected to its commercial provisions and when Philip IV became king in 1621, he resumed the war.