Brünn made a stout resistance and Prince Charles was deputed to march to its relief. At this point the heroism of the Queen seemed to be rewarded by a sudden change of fortune. Frederick tried once more to sacrifice his allies to his own profit, but in vain. England, now guided by Carteret in place of Walpole, was actively supporting Maria Theresa. Sardinia deserted the coalition against her. At Vienna, men regained a confidence which was heightened by the news from the North. Prince Charles feinted against the French in Bohemia and Frederick dismissed the Saxons to help them. This was but the first step towards the abandonment of the whole venture. After a toilsome retreat and countless skirmishes, the exhausted Prussians crossed safely into Bohemia before the end of April and again the negotiators were set to work. Once more they failed and the Prussians found themselves between Prague and the army of Prince Charles, which was now making thither from Moravia.
A conflict was inevitable. It took place at Chotusitz, near the Elbe, within three marches of Prague, on May 17, 1742. This battle is remarkable not only because seven thousand men fell in three hours, but also because it is the first victory actually won by Frederick himself. His imperious temper had cost him the services of Schwerin, the hero of Mollwitz, while the Old Dessauer had been rebuked for disobedience and sent to the rear. But the Prussian infantry were as steady as at Mollwitz, the cavalry, who suffered terribly, much better, and the King proved that he could seize the moment for decisive action on the field as well as in the cabinet. Four thousand Prussians fell, but casualties, captures, and desertion reduced Prince Charles’s force of thirty thousand by one-half.
The victory of Chotusitz assisted Frederick once more to abandon his allies. It added force to the diplomacy of England, whose policy was to help Austria a great deal against the French, but not at all against the Prussians. While the English ambassadors were urging the Queen to submit to the loss of Silesia, the Austrian troops pressed the French hard in Bohemia and thus forced Frederick to hurry on a peace. Within four weeks of Chotusitz, victor and vanquished had come to terms. Frederick withdrew from the war and received all Silesia except a fringe on the south-west, as well as the county of Glatz in full sovereignty for ever. On July 28th these terms were embodied in the Treaty of Berlin, which closed the First Silesian War. In twenty months, at a cost of two pitched battles, Frederick had added to Prussia sixteen thousand square miles of fertile land and a million and a quarter of inhabitants—a greater prize than any that his ancestors had won. He was not yet thirty-one years of age.