He rose to become a general of the Revolutionary Army, and led a division in Italy under Napoleon Bonaparte until his death in battle after being hit by friendly fire.

He was the son of Louis Philippe de La Harpe, Seigneur des Uttins and member of Lausanne's Council of Sixty, and Sophie Hugonin.

[1] He attended a philanthropinist school in Haldenstein along with his cousin Frédéric-César de La Harpe,[1] who would become the leader of the successful movement for the independence of Vaud from the canton of Bern.

[3] In 1792, in accordance with the laws of revolutionary France and his own beliefs, La Harpe dropped the nobiliary particle "de" from his surname and changed it to Laharpe.

[3] He was promoted to lieutenant-colonel of the 35th Infantry Regiment in January 1793[5] and distinguished himself at the Siege of Toulon, being rewarded with the rank of brigade general in December of that year.

After marching along the south bank of the Po River, Laharpe's division crossed near Piacenza and thrust north to turn Beaulieu's left flank.