In the army under Marshal the Count de Munich, young Loudon served in the long campaign from 1736 to 1739, and was present in that barbarous warfare in the Crimea, which is already detailed in the memoirs of the Counts Lacy and Brown, including the capture of Azoph; the storming of the lines at Perecop; the assault and capture of Oczackow, Staveoctochane and Choczim, with the general ravage and subjugation of the Tartar peninsula down to the extreme verge of the Tauric range, and to the Symbolorum Portus of Strabo--the harbour of Balaclava. In his position, which was then so subordinate, the share borne by Loudon in those brilliant operations was necessarily obscure; but, for his ability and attention to duty, he was soon raised from the rank of cadet to the commissions of a second, and then first lieutenant; a proof that the germ of an able officer had been discerned by his colonel in the foreign volunteer. The treaty which ceded Azoph to Russia in 1739 secured a brief peace to Europe, and the Empress Anne Ivanowna began to disband her unwieldly forces. On this occurring, Lieutenant Loudon repaired to St. Petersburg in 1740, for the double purpose of complaining to the Empress that he had been unjustly treated during the war, having served nine years and being still a subaltern; and also to solicit from her further employment and promotion. Disappointed in both these objects, he resigned his commission in her service with disgust, and quitted the Russian capital, resolving to make an offer of his sword to the Empress Queen of Hungary, Maria Theresa, who had succeeded her father Charles VI. on the Austrian throne, and found it assailed on all sides by hostile armies. As he passed through Berlin he fell in with several officers, principally Scots and Irishmen, with whom he had served under Marshal Munich in the late campaigns; and some of these recommended him to join the Prussian service, in which they had all accepted commissions; and one was kind enough to offer him an introduction to the warlike Frederick II., with whom, after some weeks' delay, he had the honour of an interview. Loudon modestly stated his nine years' service, his junior rank and wishes, adding that, as he had held a lieutenantcy under the Empress Anne, he ventured to hope that his Majesty would bestow upon him the command of a company. Frederick keenly scrutinized his face, which "was serious, cold, severe, reserved, pensive, and reflecting" (for he was a man schooled in danger and adversity), and it did not prepossess the royal martinet of Prussia in his favour, for he had the rudeness to turn his back upon the military stranger, and say to some officers near him,-- "_The physiognomy of this man does not please me._" In anger and mortification young Loudon, then in his twenty-fourth year, quitted his presence with a swelling heart; but he could not then foresee the time when he would become the most formidable enemy that ever met the Prussian monarch in the field.