It was at this time that Loudon with his Croats joined the Austrian army; and in the disastrous retreat which ensued after Lowositz, he narrowly escaped when a hundred of his grenadiers were slain by the Prussian hussars. During Marshal Brown's retreat out of Saxony, Loudon took by surprise the town of Estchen at the head of five hundred men, and destroyed two squadrons of Prussian hussars. This was his first exploit, and it was deemed the most brilliant of the Austrian campaign. He distinguished himself again at Hirschfeld, on the Bohemian frontier; and for his bravery on that occasion was appointed colonel in February, 1757. On the 20th of that month his corps had formed part of the six thousand Austrians who attacked the Prussian position at four in the morning. Loudon fought with incredible bravery, and slew many of the enemy with his own hand. In August he attacked the Schriekstein and captured three hundred newly raised soldiers. He now obtained an increased command--a small division, six thousand strong, consisting of Croats and Pandours. With these he attacked and defeated a body of the enemy at Erfurth, a garrison town of Saxony. He then joined the now allied French and Imperialists, who marched to Weissenfels, a city in the centre of Thuringia. By this time the Swedes were pushing on the war in Pomerania and had besieged Stettin. Marshal Richelieu with eighty battalions and one hundred squadrons of French had entered Halberstadt, and was everywhere levying contributions with fire and sword, while the Austrians had made themselves masters of Lignitz and most of Silesia; and after laying siege to Schwiednitz, were preparing to pass the Oder. Everywhere the tide of war had turned upon the King of Prussia. Loudon was now with what was named the _Combined Army_. The Prince de Soubise commanded the French; the Prince of Hildburghausen led the Austrians, and their united and immediate object was to clear Saxony of the Prussians. Frederick left a division to cover Silesia, and approached this Combined Army, which passed the Sala and established its head-quarters at Weissenfels; from whence the Comte de Mailly was sent to summon Leipzig. On the 5th November, the King of Prussia gave battle to this Combined Army, then fifty thousand strong, at Rosbach, a village of Prussian Saxony, at eleven o'clock in the morning. The allies were formed in line with their cavalry in front. The impetuosity of the Prussian infantry, whose charge was admirably sustained by a fire of artillery and advance of horse, broke the allied line, and, notwithstanding all the efforts of the Prince de Soubise, Frederick obtained a complete victory with the loss of three hundred men only; while the Combined Army lost no less than eleven generals, three hundred other officers, nine thousand killed, wounded, and prisoners, sixty-three guns, twenty-nine colours, and one pair of kettle-drums. With the battle of Rosbach terminated the campaign in Saxony.