Promoted to general officer during the French Campaign in Egypt and Syria, he returned to France where he held several non-combat posts.

At Prenzlau he led a highly successful charge against forces of the Kingdom of Prussia, capturing many soldiers and cannon.

He was exchanged and fought in many battles at the head of Marshal Louis Gabriel Suchet's cavalry during the Peninsular War.

In that year, he quit the Austrian army and transferred his loyalty to the United States of Belgium at the time of the Brabant Revolution.

[1] Transferred to the Army of Italy as a chef d'escadron (major) of the 20th Dragoon Regiment, Boussart fought at the Battle of Mondovì on 21 April 1796.

[1] In the War of the Third Coalition against Austria, Boussart led a brigade in Frédéric Henri Walther's 2nd Dragoon Division.

[2] During the War of the Fourth Coalition against Prussia, Boussart led the 3rd Brigade in Emmanuel Grouchy's 2nd Dragoon Division.

[3] Grouchy's division missed the Battle of Jena-Auerstedt but became deeply involved in the pursuit of the defeated Prussian armies.

At Zehdenick on 26 October, Grouchy's division crushed a 1,300-man Prussian brigade, decimating the Königin Dragoon Regiment Nr.

Marshal Joachim Murat led Grouchy's division, Marc Antoine de Beaumont's 3rd Dragoon Division, Antoine Lasalle's light cavalry brigade, and 3,000 of Marshal Jean Lannes' infantry against Frederick Louis, Prince of Hohenlohe-Ingelfingen's 12,000 Prussians.

[9] On 2 and 3 November, the 22nd Dragoons of Boussart's brigade secured the surrender of the small port of Wolgast on the Baltic Sea.

The dragoons first drove off the Russian cavalry menacing Louis Vincent Le Blond de Saint-Hilaire's infantry division.

After being rebuffed by the Russian second line, Grouchy's troopers joined the Horse Grenadiers of the Imperial Guard and smashed their way through.

[18] In fact, Theodor von Reding's 17,000-man Spanish corps arrived at Bailén on the 18th and occupied the town without opposition.

[20] While Dupont and the French generals were returned to France, the enlisted men spent the rest of the war in prison hulks or on the bleak island of Cabrera and half of them died of disease or starvation.

[21] In January 1810, Boussart next appeared in the French order of battle in Spain at the head of Suchet's 1,899-strong III Corps cavalry.

By 2 January 1811, the Siege of Tortosa was concluded after the French inflicted 1,400 casualties on the defenders, while suffering only 400 killed and wounded.

[29] In late summer, Suchet launched an invasion of the province of Valencia, arriving before the ancient fortress of Saguntum (Sagunto) on 23 September 1811.

[30] After the garrison repelled two French assaults, a relief army of Joaquín Blake y Joyes appeared and the two sides clashed in the Battle of Saguntum on 25 October.

While the French dispersed Blake's left flank rather easily, the fighting in the center and right of the Spanish line was much tougher.

[1] Hewing a path through their opponents, the armor-clad heavy cavalrymen captured a Spanish artillery battery before their impetus was spent.

For a loss of 1,000 casualties, the French inflicted 6,000 killed and wounded on the Spanish, not counting several hundred prisoners.

[32] In the operations immediately preceding the Siege of Valencia, Suchet concentrated most of his army in an envelopment of the landward flank of Blake's defenses.

[33] Led by one squadron of the 4th Hussars, Jean Isidore Harispe's division reached a position behind the Spanish left flank.

[1] After Harispe and the French cavalry routed the Spanish troopers, they found Boussart lying among the fallen after having been robbed of his medals and sword.

However, the flank was protected by waterlogged ground, so the cavalry general could only observe his enemies as Suchet's main attack was defeated.