In this phase of the war Protestantism and Catholicism, tolerance and intolerance, ceased to be the immediate objects of the strife. The possession of Alsace and Lorraine rose into primary importance, not because, as in our own days, Germany needed a bulwark against France, or France needed a bulwark against Germany, but because Germany was not strong enough to prevent these territories from becoming the highway of intercourse between Spain and the Spanish Netherlands. The command of the sea was in the hands of the Dutch, and the valley of the Upper Rhine was the artery through which the life blood of the Spanish monarchy flowed. If Spain or the Emperor, the friend of Spain, could hold that valley, men and munitions of warfare would flow freely to the Netherlands to support the Cardinal-Infant in his struggle with the Dutch. If Richelieu could lay his hand heavily upon it, he had seized his enemy by the throat, and could choke him as he lay. [Sidenote: § 5. Richelieu asks for fortresses in Alsace.] After the battle of Nördlingen, Richelieu's first demand from Oxenstjerna as the price of his assistance had been the strong places held by Swedish garrisons in Alsace. As soon as he had them safely under his control, he felt himself strong enough to declare war openly against Spain. [Sidenote: § 6. War between France and Spain.] On May 19, eleven days before peace was agreed upon at Prague, the declaration of war was delivered at Brussels by a French herald. To the astonishment of all, France was able to place in the field what was then considered the enormous number of 132,000 men. One army was to drive the Spaniards out of the Milanese, and to set free the Italian princes. Another was to defend Lorraine whilst Bernhard crossed the Rhine and carried on war in Germany. The main force was to be thrown upon the Spanish Netherlands, and, after effecting a junction with the Prince of Orange, was to strike directly at Brussels. SECTION II.--_Spanish Successes._ [Sidenote: § 1. Failure of the French attack on the Netherlands.] Precisely in the most ambitious part of his programme Richelieu failed most signally. The junction with the Dutch was effected without difficulty; but the hoped-for instrument of success proved the parent of disaster. Whatever Flemings and Brabanters might think of Spain, they soon made it plain that they would have nothing to do with the Dutch. A national enthusiasm against Protestant aggression from the north made defence easy, and the French army had to return completely unsuccessful. Failure, too, was reported from other quarters. The French armies had no experience of war on a large scale, and no military leader of eminent ability had yet appeared to command them. The Italian campaign came to nothing, and it was only by a supreme effort of military skill that Bernhard, driven to retreat, preserved his army from complete destruction. [Sidenote: § 2. Spanish invasion of France.]