So long as Prince Baltasar lived Philip resisted all pressure that he should take another wife. The spring and summer were spent in Aragon, in the now almost despairing attempt to win back his dominions from the French. Approaches for his own marriage were made by various interests, but always gently put aside with a reference to his hopes being now centred in his son, whom he kept at his side and instructed him in the business of government. With a wretched lack of material resources his attempts to recover Catalonia were fruitless. One defeat followed another with wearisome reiteration, and as disaster deepened Philip became more moody and devout; his one adviser and confidant being the nun of Agreda, and his one resource agonised prayer. When his boy fell ill in May 1646, at Pamplona in Navarre, on his way to the seat of war, Philip’s invocations to heaven for his safety were almost terrible in their intensity.[233] The lad recovered; and when he arrived with his father at Saragossa in July, the imperial ambassadors were awaiting them to offer in marriage to the heir of Spain his first cousin, the Archduchess Mariana of Austria, the daughter of the Emperor. Philip could look nowhere else for an alliance. France was his deadly enemy, though it was governed by his sister Anna as regent, and a further marriage experiment in that direction was out of the question at present, even if there had been an available French princess.[234] The Emperor and Spain, on the other hand, had been—to Spain’s ruin—fighting shoulder to shoulder throughout the whole of the thirty years’ war, now dragging to its conclusion, and the treaty was promptly signed for the marriage of Baltasar, aged seventeen, with Mariana of Austria, three years younger. With regard to their betrothal, Philip wrote to the nun thus: ‘My sister, the Empress, having died, I consider it advisable to draw closer the ties between the Emperor and ourselves in this way, my principal aim being the exaltation of the faith; for it is certain that the more intimate the two branches of our house are, so much the firmer will religion stand throughout Christendom.’ Only two months later, early in October, the blow fell, and the prince died of smallpox. Whilst he lay ill the distracted father wrote frantically to his correspondent, crying for God’s mercy to save him from this last trial. But when the boy had died the King’s letters assumed a tone of dull despair. God had not heard his prayers, and he supposed it was for the best. He had done everything to dedicate this grief to God; but his heart was pierced, and he knew not whether he lived or dreamed. He was resigned, he said, but feared his constancy, and so on; each phrase revealing a heart that almost doubted the efficacy of prayer, and the goodness of the Almighty.[235]