Reynier participated in Napoleon's conquest of Malta and the following Egyptian campaign in 1798, commanding a division at the Battle of the Pyramids and, in 1799, at the sieges of El Arish and Acre. Later, under the command of General Jacques-Francois Menou he defended against the British counter-invasion of Egypt in 1801. His division was present but not engaged in the Battle of Alexandria. After returning to France, Reynier killed a fellow general in a duel and was under a cloud for a time.