Finding the day irreparably lost, Count Lacy, Prince Charles of Lorraine, the Princes of Saxony and Modena, and the Duke d'Aremberg, with the remnant of their infantry, in all 50,000 men, took refuge in Prague, where the gallant Brown expired of his wound, on the 6th May. Meanwhile 16,000 cavalry fled to Marshal Daun, who had encamped at Bohmishbrodt the night before the battle.
The Prussians followed up their victory with ardour; Prague, with 100,000 souls within its walls, was invested closely; Frederick pushed the blockade on one side, and Marshal Keith on the other. In four days they had it completely surrounded, and cut off every means of supply, agreeably to the last words of Marshal Brown, who, when dying, said: "Tell Prince Charles of Lorraine instantly to march out and attack Marshal Keith, or all is lost."
Lacy and others proposed to assail the Prussians in the night, with 12,000 Austrians, who were to be sustained by all the Pandours and Hungarian Grenadiers; and thus to hew a passage, sword in hand, through Frederick's lines, and relieve Prague of the multitude of soldiers who were rapidly consuming the provisions of the people. An infamous deserter informed the Prussians of this gallant design, and thus they were all on the alert, when about two o'clock, in the darkness of a misty morning, a fiery tide of armed men rolled out of Prague, and assailing Marshal Keith at the bayonet's point, pressed desperately on towards the Moldau; but, after a fierce and desultory conflict, in which Prince Henry (Frederick's youngest son) had a horse shot under him, the Austrians were routed, and Lacy and other brave leaders were forced to fall back into Prague, with the loss of many killed and wounded.
After this the Prussian batteries opened, and in twenty-four hours threw 300 bombs, besides many fire-balls into the town; its streets were soon sheeted with fire, and men, women, and horses, with the sick and wounded, perished in vast numbers. The city burned for three days; flames and starvation drove the citizens to despair. Seeing their loved Bohemian capital on the verge of destruction, they besought Lacy, d'Aremberg, and other commanders, in the most moving terms, to surrender; but war had hardened their hearts, and instead of complying, they drove out 12,000 persons who were considered as a mere incumberance. These unfortunates were hurled back by the Prussians to the walls of Prague, and thus the Austrians were soon reduced to eat their troop and artillery horses, forty of which were shot daily, and cut up for rations, or sold at four pence per pound to the wretched people, who still perished hourly by fire, shot, and famine.
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 manœuvres 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.
He served valiantly at the great battle of Hochkirchen, when the good old Marshal Keith, Knight of the Black Eagle, and Governor of Berlin, a general second to none in the Seven Years' War, was slain that day, when lighting on foot at the head of the Prussian infantry; and here ensued an affecting incident. After the battle, his body was shamefully abandoned by the routed Prussians, and stripped by Austrian stragglers. Thus it lay long on the field, undistinguished from the thousands of others which covered it. In this degrading situation it was found by Lacy, who was riding over the ground, and with whose father (old Marshal Lacy) the venerable Keith had served in Prussia, and by whose side he had been wounded in the Crimea. The count recognised the body, says Dr. Smollett, by the large scar of a dangerous wound which General Keith had received in his thigh at the siege of Oczakow, and could not refrain from tears on seeing his father's honoured friend lying thus at his feet, a naked, lifeless, and deserted corpse; and it must have been an interesting scene to witness these two exiles—the young Irish Jacobite weeping over the old Scottish Cavalier—on that sanguinary field. Lacy had the body immediately covered, and interred with the honours of war, in the adjacent churchyard, from whence it was afterwards removed to Berlin.
Lacy, with Daun and Loudon, bore a conspicuous part in the campaign of 1760, particularly in those manœuvres by which the King of Prussia, notwithstanding all his skill and cunning, was frustrated in his Silesian operations.