Lecointe took part in the Crimean War (1854–1856) as a battalion commander attached to the army of "Général de division" Pierre Bosquet and participated in the Battle of the Alma on 20 September 1854 and the Battle of Malakoff on 8 September 1855. In 1857 he took part in the Algeria in the Campaign of Kabylie in Algeria during the pacification of Algeria and seized Borj Mawlay Hasan (known to the French as Fort l'Empereur).