The attention and resources of Austria were fully occupied, and the Prussians were almost unopposed. One column passed through Saxony, another through Lusatia, while a third advanced from Silesia. Prague, the objective, was reached on the 2nd of September. Six days later the Austrian garrison was compelled to surrender, and the Prussians advanced to Budweis. Maria Theresa once again rose to the emergency, a new "insurrection" took the field in Hungary, and a corps of regulars was assembled to cover Vienna, while the diplomatists won over Saxony to the Austrian side. Prince Charles withdrew from Alsace, unmolested by the French, who had been thrown into confusion by the sudden and dangerous illness of Louis XV. at Metz. Only Seckendorf with the Bavarians pursued him. No move was made by the French, and Frederick thus found himself after all isolated and exposed to the combined attack of the Austrians and Saxons. Marshal Traun, summoned from the Rhine, held the king in check in Bohemia, the Hungarian irregulars inflicted numerous minor reverses on the Prussians, and finally Prince Charles arrived with the main army. The campaign resembled that of 1742; the Prussian retreat was closely watched, and the rearguard pressed hard.

Prague fell, and Frederick, completely outmanoeuvred by the united forces of Prince Charles and Traun, regained Silesia with heavy losses. At the same time, the Austrians gained no foothold in Silesia itself. On the Rhine, Louis, now recovered, had besieged and taken Freiburg, after which the forces left in the north were reinforced and besieged the strong places of Flanders. There was also a slight war of manoeuvre on the middle Rhine.

In 1744 the Italian war became for the first time serious. A grandiose plan of campaign was formed, and as usual the French and Spanish generals at the front were hampered by the orders of their respective governments. The object was to unite the army in Dauphiné with that on the lower Po. The adhesion of Genoa was secured, and a road thereby obtained into central Italy. But Lobkowitz had already taken the offensive and driven back the Spanish army of Count de Gages towards the Neapolitan frontier. The king of Naples at this juncture was compelled to assist the Spaniards at all hazards. A combined army was formed at Velletri, and defeated Lobkowitz there on the 11th of August. The crisis past, Lobkowitz then went to Piedmont to assist the king against Conti, the king of Naples returned home, and de Gages followed the Austrians with a weak force. The war in the Alps and the Apennines was keenly contested. Villefranche and Montalban were stormed by Conti on the 20th of April, a desperate fight took place at Peyre-Longue on the 18th of July, and the king of Sardinia was defeated in a great battle at Madonna del Olmo (September 30) near Coni (Cuneo). Conti did not, however, succeed in taking this fortress, and had to retire into Dauphiné for his winter quarters.

The two armies had, therefore, failed in their attempt to combine, and the Austro-Sardinians still lay between them.

8. Campaign of 1745. - The interest of the next campaign centres in the three greatest battles of the war - Hohenfriedberg, Kesselsdorf and Fontenoy. The first event of the year was the Quadruple Alliance of England, Austria, Holland and Saxony, concluded at Warsaw on the 8th of January. Twelve days previously, the death of Charles VII. submitted the imperial title to a new election, and his successor in Bavaria was not a candidate. The Bavarian army was again unfortunate; caught in its scattered winter quarters (action of Amberg, January 7), it was driven from point to point, and the young elector had to abandon Munich once more. The peace of Füssen followed on the 22nd of April, by which he secured his hereditary states on condition of supporting the candidature of the grand-duke Francis, consort of Maria Theresa. The "imperial" army ceased ipso facto to exist, and Frederick was again isolated. No help was to be expected from France, whose efforts this year were centred on the Flanders campaign.

In effect, on the 10th of May, before Frederick took the field, Louis XV. and Saxe had besieged Tournay, and inflicted upon the relieving army of the duke of Cumberland the great defeat of Fontenoy (q.v.). In Silesia the customary small war had been going on for some time, and the concentration of the Prussian army was not effected without severe fighting. At the end of May, Frederick, with about 65,000 men, lay in the camp of Frankenstein, between Glatz and Neisse, while behind the Riesengebirge about Landshut Prince Charles had 85,000 Austrians and Saxons. On the 4th of June was fought the battle of Hohenfriedberg (q.v.) or Striegau, the greatest victory as yet of Frederick's career, and, of all his battles, excelled perhaps by Leuthen and Rossbach only. Prince Charles suffered a complete defeat and withdrew through the mountains as he had come. Frederick's pursuit was methodical, for the country was difficult and barren, and he did not know the extent to which the enemy was demoralized. The manoeuvres of both leaders on the upper Elbe occupied all the summer, while the political questions of the imperial election and of an understanding between Prussia and England were pending.

The chief efforts of Austria were directed towards the valleys of the Main and Lahn and Frankfort, where the French and Austrian armies manoeuvred for a position from which to overawe the electoral body. Marshal Traun was successful, and the grand-duke became the emperor Francis I. on the 13th of September. Frederick agreed with England to recognize the election a few days later, but Maria Theresa would not conform to the treaty of Breslau without a further appeal to the fortune of war. Saxony joined in this last attempt. A new advance of Prince Charles quickly brought on the battle of Soor, fought on ground destined to be famous in the war of 1866. Frederick was at first in a position of great peril, but his army changed front in the face of the advancing enemy and by its boldness and tenacity won a remarkable victory (September 30). But the campaign was not ended. An Austrian contingent from the Main joined the Saxons under Marshal Rutowski, and a combined movement was made in the direction of Berlin by Rutowski from Saxony and Prince Charles from Bohemia. The danger was very great.