In mid-October 1831 Louis Philippe I sent de Mornay on a mission to Abd al-Rahman of Morocco.

His task was to negotiate a peace treaty and a border delimitation with the Alawite emperor.

Following the French conquest of Algeria the mission needed to establish neighbourly relations between the two countries.

[1] His mission had an immediate success: On April 4, 1832 he was able to send a letter declaring to the general-in-chief of the staff of Algiers, Anne Jean Marie René Savary, that Morocco would abandon its claims on the region of Tlemcen and Oran, promise to remain neutral and withdraw their troops from Algeria.

At first Eugène Isabey had been approached to join the diplomatic mission to North Africa.