Two other sallies were made, and the Prussian camp was kept in a state of perpetual alarm. In this defence, so disastrous to the city, Lacy was of incalculable service in harassing the Prussian trenches, by his vigilance and restless bravery. Contrary to the advice of Keith, the king, on the 13th of June, left a small force before Prague, and, drawing off his main body, marched against Daun, who defeated him in battle at Kolin, and forced him to leave Bohemia--a movement by which the blockade of Prague was abandoned; and the imprisoned Austrians received their deliverer with inexpressible joy. Lacy and other generals issued out, with their breasts full of ardour and vengeance, and followed the retreating Prussians over the Saxon frontier, sabring all stragglers who fell into their power.
To narrate all the military operations in which Count Lacy bore a part, would be to rehearse the history of the Seven Years' War. He owed his elevation and high consideration as much to his own bravery and skill as to the patronage and friendship of Daun, who consulted him on every occasion, and employed him in the execution of the most delicate measures.
Though by his vigour and decision he frequently urged Marshal Daun on many a bold enterprise, he was possessed of great coolness and presence of mind. "His ardour," says the historian of the House of Hapsburg, "never exceeded the bounds of prudence, or hurried him into attempts which might incur the censure of his patron." He was of great service in drilling and training the Austrian forces to perform those new and difficult manoeuvres of which Daun was the inventor; he was a strict disciplinarian, a friend to order, and by his precept and example succeeded in introducing a degree of economy into every branch of the Austrian military service.
In 1758 the King of Prussia commenced the new campaign, and entering Moravia, invested Olmutz. General Lacy was then of great service in protecting the roads which led to Upper Silesia; and, when posted at Gibau with a large body of Austrians, he sent a detachment of grenadiers to Krenau, where they harassed the Prussian rear-guard, till they were driven back by Wied. When Frederick retired from Konigsgratz, Lacy and St. Ignan followed him with 15,000 men, and had many severe encounters with the Putkammer hussars, who formed the rear guard of the Prussians.