Spain responds in early 1635 to France's…
December 1635 CE
Spain responds in early 1635 to France's increasingly belligerent posturing by intervening against the Elector of Trier, a significant move that effectively forces a French declaration of war.
By this stage, Olivares' advice to the king is that this conflict with France will be for all or nothing: Spain will win or fall by the result.
Nonetheless, French victory is far from certain in the 1630s; Olivares' invasion plan in 1635 involves four different armies and two navies, being described as 'the most ambitious military conception of early modern Europe.'