In the war of the Hungarian Succession, after the cowardice and extraordinary mismanagement of the Duke of Cumberland had covered the British army with disgrace in the Low Countries, by allowing it to be outflanked at Khloster Seven, by failing to defend the position at Maestricht, and forcing it shamefully to capitulate, on the 8th of September, 1757, and thus abandon our ally, Frederick the Great of Prussia, that warlike monarch only pushed on the war with greater vigour. In this disastrous contest the activity and vigilance of Count Lacy soon recommended him to the notice of Leopold Count Daun, a native of Bohemia, and son of Philip Lorenzo, Prince of Tiano, the pupil of Kevenhüller; and he improved the good opinion of that great soldier by his fascinating manner and courtier-like behaviour. The friendship of Daun soon won him the rank of major-general; and as such he commanded a brigade in his division, when, in 1757, conformable to the defensive system taken by Russia, Austria, and Sweden, the army of the Empress-Queen was broken into four great columns, to prosecute the war against the Prussians, French, and Bavarians, the violators of the famous Pragmatic Sanction.
One column, under the Duke d'Aremberg, was posted at Egra; a second, under Marshal Count Brown, was posted at Budyn; a third, under Count Konigsegg, held Reichenburg; a fourth, under Marshal Daun, occupied Moravia.
In his column were the brigades of Lacy and Lowenstein, whom Frederick of Prussia styles "two young officers who ardently sought to distinguish themselves." Lacy was then in his thirty-eighth year.
In Lusatia, during the winter of 1756 and the spring of 1757, these officers had given infinite trouble to the troops of Frederick. They had frequently attacked, sword in hand, his post at Ostritz, a Saxon town on the Queiss; at other times, his intrenchments at Hirschfelde, a manufacturing town on the left bank of the Neisse, and also at Marienthiel. Hirschfelde, which was garrisoned by one battalion of Prussians, they assailed at four o'clock one morning, with 6000 men; two redoubts, which stood without the gates, each defended by two pieces of cannon, were repeatedly taken and retaken; but after losing 500 men, Lacy and his brother-brigadier retired, bringing off the Prussian guns as a trophy. These assaults were ineffectual, and many men were slain. Among others fell Major Blumenthal, of the Prince Henry's regiment--a brave officer. The Prussian corps of Lestwitz at Zittace, and of the Prince of Bavern at Gorlitz were harassed by perpetual alarms; and such was the activity of young Lacy and Lowenstein, that they kept them continually under arms, if not in action, during the winter months.