Spain's increased tensions with France make war between the two Catholic states increasingly inevitable, despite fresh Spanish successes in the mid-1630s—in particular, the triumph of Philip's government in raising a fresh Spanish army in northern Italy and marching it into Germany under the leadership of Cardinal-Infante Ferdinand to defeat the Swedish-lead Protestant forces at the Battle of Nördlingen in 1634.

The scene has been set, Olivares believes, for a renewed attack on the Dutch, but Olivares' strategy ultimately fails due to the entry of France into the war.

His handling of War of the Mantuan Succession, which had started to pitch France against the Habsburgs in northern Italy and will ultimately result in the French invasion of Spain, has been much criticized.

France, seeing the Spanish successes in Germany and the defeat of her Swedish allies by 1634, begins raising the political stakes, taking provocative military action on a small scale.