[2] After the French occupation of Malta in 1798, Tousard left with Napoleon to the Egyptian campaign.

After the capture of Alexandria, he was appointed deputy director of the fortifications, and was wounded during the Battle of Aboukir Bay on 2 August 1798.

He was appointed Chef de Brigade on 5 February 1801 by General Menou.

In 1806 and 1807 he took part in the campaigns of Prussia and Poland, including the Battles of Jena, Eylau, Heilsberg and Friedland.

He was promoted to brigadier general on 5 July 1807, and was in control of the engineering of the 3rd Corps stationed in the Duchy of Warsaw between 1808 and 1809.