Vauvenargues was twenty-six years of age when the war of the Austrian Succession broke out, and swept him into military action. He was vegetating in garrison at Metz when the armies of Marshal de Belle-Isle, the gallant and thrice-unfortunate, streamed eastward into Germany and carried our philosopher with them. The Regiment of the King, of which Vauvenargues was an officer, reached Bohemia in July 1741. In a night attack of extraordinary rapidity and audacity Prague was captured, and Vauvenargues took a personal part in this adventure, which must have cast fuel on the fire of his rising military ambition. But the conduct of war is all composed of startling ups and downs, and at the height of the successes of the French, their luck abandoned them. Relieved by no reinforcements and pressed hard by famine, the army of Belle-Isle could no longer hold Prague, and on the night of December 16-17, 1742, began the retreat from Bohemia which is one of the most noted disasters of the eighteenth century. Nine days later, what remained of the French army arrived at Egra, but after a march through thick fog over frozen ground, without food, without shelter, in a chaotic frenzy of despair. Vauvenargues was one of those who never recovered from the agony of the retreat from Prague. Both his legs were frost-bitten, so that for the remainder of his life he was lame; his eyesight was permanently impaired; and he appears to have sown the seeds of the pulmonary disease which was to carry him off five years later. But his tender heart endured what were still severer pangs from the sufferings and death of those of his companions for whom he had the greatest regard. Among these the first place was held by Hippolyte de Seyres, whose figure pervades the earliest developments of the genius of Vauvenargues. De Seyres was a lieutenant in the philosopher's regiment. He was only eighteen years of age, and Vauvenargues felt for him the interest of an elder brother and the affection of a devoted friend. We can trace the progress of the sentiment, in which are fully revealed for the first time the peculiar qualities of our author's mind. He does not conceal from himself the weaknesses of the character of De Seyres, he blames him for his lack of suppleness, of simplicity of manner, of self-confidence. He found in him a proud and delicate spirit which exaggerated its own frailties and shrank morbidly from their consequences. He was anxious that the spirit of the young man should not be debased by low associations; he did not think the slightly older officers who surrounded De Seyres to be wholesome companions for him. The lad displayed a lack of moral force; he hoped to succeed less by his own exertions than by the favour of others; he was in despair over his own faults without having the energy to correct them. It is in writing about De Seyres that Vauvenargues first defines his central axiom, that the only sources of success are virtue, genius and patience.