Boussart went with Napoleon Bonaparte to Egypt and fought at the Battle of the Pyramids on 21 July 1798 and the Battle of Abukir on 25 July 1799. He was named general of brigade on 23 September 1800, which was confirmed when he got back to France. In the Battle of Alexandria on 21 March 1801, he fought against the British. Wounded three times in the action, he required several months of convalescence. At the end of the Siege of Alexandria on 2 September 1801, he was ordered to sign the articles of capitulation. He became a member of the legion d'honneur on 11 December 1803 and served in the Bordeaux military district as a dragoon commander.