In the next campaign, at Ho-henfriedberg, he defeated a joint army of Austrians and Saxons (June 4, 1745), in a manner which placed him at the head of contemporary commanders. This victory was followed by those of Sorr (Sept. 30) and Kesselsdorf (Dec. 15), and the fall of Dresden; and having no longer reason to fear that Maria Theresa could avenge herself, he deserted his French ally, and made peace with Austria and Saxony by the treaty of Dresden (Dec. 25), by which he acknowledged Francis as emperor, and was confirmed in the possession of Silesia. Fred-crick by this time had doubled the number of his subjects, and had succeeded so well in humbling Austria and her allies, that he appeared to hold in his hand the balance of power in Germany. His people now enjoyed 11 years of peace, during which he devoted himself to the organization of his states and his army, the advancement of the arts, agriculture, manufactures, commerce, and education, the amelioration of the laws, and the increase of the public revenues. He also wrote his Memoires pour servir a l'histoire de Brandebourg (2 vols., Berlin, 1751), his poem l'Art de guerre, and many other productions in prose and verse.

This was a period, nevertheless, of constant anxiety and insecurity; and learning in 1756 that a new coalition, including Russia and his former ally France, was forming against him, Frederick at once prepared for the encounter, suddenly allied himself with England, and the whole face of affairs was changed. Sweden, the tool of France, followed the French leading; and Frederick, with scarcely 5,000,000 subjects, including the conquered Silesians, found himself alone on the continent against nearly 100,000,000. It was resolved to crush him; but he had foreseen this design, detected all the secret intrigues, and resolved to strike the first blow. In August, 1756, with 70,000 men, he entered Saxony, and commenced the famous seven years' war. His army had grown to 160,000 men, but his enemies could bring 600,000 troops into the field, and there was not a politician in Europe who did not look upon his destruction as certain. He himself thought it probable; but he had an overflowing treasury at home, and plenty of money from England, and he hoped that genius, judgment, and resolution, with ordinary good fortune, might at least sustain him until his enemies should quarrel among themselves. At Dresden he seized some state papers which exposed the designs of the coalition.

They were published, and the world saw that this time he had right on his side. He defeated the Austrian general Braun at Lowositz (Oct. 1); the Saxon army under Rutowski surrendered a fortnight later, and the whole of Saxony was reduced, and became virtually a part of Frederick's dominions. He levied troops and supplies; and thus, within a few weeks, one of the confederates was made to turn his weapons against the others. The next campaign opened with the great battle of Prague, May 6, 1757. Frederick was victorious, but lost 12,000 men, and among them his general Schwerin. A second battle was fought and lost against Daun at Kolin, June 18. Frederick abandoned Bohemia. French troops invaded Prussia, and his army lost confidence. French, Swedes, and Russians were marching upon Berlin; and Frederick, mourning the death of his mother, whom he tenderly loved, provided himself with poison, and meditated suicide. He marched from Bohemia against the French, and with half their numbers defeated them at Rossbach, and took 7,000 prisoners (Nov. 5). He now turned against the Austrians, who had entered Berlin, and captured Schweidnitz and Breslau. On Dec. 5, at Leuthen, with 30,000 men, he attacked 80,000, killed or captured 27,000, and took 130 guns, 50 standards, and 4,000 wagons.

Early in 1758, having previously recovered Breslau, he was again ready for action, recaptured Schweidnitz, and with 37,000 troops fought almost hand to hand with 60,000 Russians at Zorndorf (Aug. 25). It was the fiercest and bloodiest battle of the war. Frederick ordered that no quarter should be given, so enraged was he with the devastations committed by the invaders; and 19,000 Russians and 11,000 Prussians lay upon the field, dead or wounded, at the close of this fearful day. The Russians abandoned Prussia, and Frederick marched into Saxony. He had beaten French, Austrian, and Russian armies in turn, each with more than double his force; but close upon these triumphs followed a chain of disasters which would have overthrown any other commander. At dead of night he was surprised and terribly defeated by Daun at Hochkirch (Oct. 14), but rallying in an incredibly short time he rescued Dresden from an overwhelming army of Austrians, and went into winter quarters at Breslau. The year 1759 saw the Austrians overrunning Saxony, Russians victorious upon the Oder, Frederick utterly routed by Soltikoff and Laudon at Kuners-dorf, Aug. 12 (where he lost two thirds of his troops), and Berlin saved only by the king's miraculous energy.

Dresden was taken by the troops of the empire, and near it Gen. Fink surrendered 12,000 Prussians. The fifth year saw the capital in the hands of the Russians, while Frederick won great battles at Liegnitz, Aug. 15, 1760, and Torgau, Nov. 3, the one over Laudon, and the other over Daun. The sixth year was also unfavorable, but he still fought on. The circle seemed to be closing around him, and he grew savage with despair. Eugland, after the death of George II., deserted him, but Russia, on the death of Elizabeth (1762), withdrew from the coalition. Frederick broke into Silesia and defeated the Austrians at Burkersdorf, and his brother Henry was successful at Freiberg. France withdrew her armies, declaring future neutrality; and Prussians and Austrians stood alone against each other. The empress now gave way, and in February, 1763, peace was signed at Huberts-burg, leaving Frederick in possession of Silesia, the sole object, short of saving Prussia itself, for which he had fought. After an absence of eight years he reentered Berlin in triumph.