During the Seven Years' War he served first as an infantry officer and later on the staff of Feldmarschall Leopold Joseph von Daun.

"As a young man, his bold and fiery character combined with his great energy and constant activity had made him well-suited to the military life.

[2] For his services, in 1790, the Habsburg army promoted him to Feldmarschall-Leutnant[3] and awarded him the Commander's Cross of the Military Order of Maria Theresa.

With 5,000 Austrian troops and 18 artillery pieces, he defeated Armand Louis de Gontaut, Duke of Biron's 7,500 soldiers and 36 guns, inflicting 400 casualties for a loss of only 30.

[6] At the unsuccessful siege of Lille from 25 September to 8 October, he commanded a division in the army of Duke Albert of Saxe-Teschen.

His command included three and a half infantry battalions under Karl von Biela, nine cavalry squadrons led by Ludwig Franz Civalart d'Happoncourt, eight squadrons commanded by Charles Eugene, Prince of Lambesc, and Karl Friedrich von Lindenau's sappers and pontonniers.

[4] On 4 March 1796, Beaulieu was promoted to Feldzeugmeister and transferred to command the 32,000-strong Habsburg army in northern Italy.

These instructions prevented Beaulieu from effectively cooperating with the Sardinian commander of the Piedmontese forces, Michelangelo Colli-Marchi, a personal friend.

Hastily, Beaulieu withdrew his army to the east, dropping off a force under Karl Philipp Sebottendorf to hold the bridge over the Adda River at Lodi.

Bonaparte seized the bridge in the Battle of Lodi on 10 May and drove Sebottendorf back with losses of 2,000 casualties and 14 guns.

A minor defeat at the Battle of Borghetto on 30 May forced Beaulieu to abandon the Mincio line and retreat north to the Tyrol.

Thomas Graham, a British observer with the Habsburg army, noted that Beaulieu seemed to expect too much from his soldiers, was irritated and tended to blame the failure of his plans on others for not properly executing his orders.

[18] After Borghetto, Emperor Francis II replaced Beaulieu with Dagobert Sigmund von Wurmser.