After transferring to the Army of the Western Pyrenees as chief of artillery, he coolly directed the successful defence of the Sans Culottes Camp in February 1794.

[2] He joined the Black Musketeers of the Maison du Roi and later in 1759[note 1] he transferred to the carabiniers with the rank of cornet.

The Minister of War Étienne François, duc de Choiseul, noting Lespinasse's intelligence, assigned him to write a treatise on practical trigonometry and leveling.

Other officers were jealous of his promotion and he was obliged to fight a number of duels in which he showed himself courageous and generous.

On 25 May 1788 he received promotion to major and put in charge of setting up an artillery depot on the Loire River, but the French Revolution ended that project.

His fertile mind came up with the idea of forming armorer companies to repair the stockpile of captured Spanish muskets.

The 26 best battalions were distributed among the front-line divisions of Jean Henri Guy Nicolas de Frégeville, Bon-Adrien Jeannot de Moncey and Henri François Delaborde while the remaining 14 were parceled out to the divisions of Jean-Antoine Marbot and Jean Mauco.

[7] The Spanish commander Captain General Ventura Caro y Fortas determined to seize two strong redoubts near Hendaye called the Croix des Bouquets and the Calvaire d'Urrugne.

[6] On 5 February 1794, 13,000 Spanish infantry and 700 cavalry and gunners under Urrutia attacked the French defenses in the Battle of Sans Culottes Camp.

Sacrificing his outlying positions he concentrated his strength at the Redoubt de la Liberté and a bitter fight ensued.

A unit of French marines suffered heavy losses while on the other side the Irish Regiment of Ultonia was roughly handled.

With the Spanish advance checked, Frégeville arrived on the scene[6] and Lespinasse offered to hand over command to his superior.

[10] Muller sent Moncey's 10,000-man division into the Baztan over the Maya Pass while Delaborde struck south from Biriatou toward Bera with 6,000.

The Baztan was quickly overrun and soon a 12,000-man force at Lesaka threatened the right rear of the Spanish positions on the lower Bidasoa.

[1] In the aftermath of their victory, the French bluffed their adversaries into surrendering both the fortresses of Fuenterrabia[12] and San Sebastián.

On 8 June, he, Jean-Mathieu-Philibert Sérurier and François, marquis de Chasseloup-Laubat reconnoitered the fortress of Mantua.