Composed exclusively of volunteers, the first Legion regiment was involved in Algeria in 1832 and then another was raised to fight in the Crimean War (1854-56), Italy's fight for freedom from Austria in 1859 and then to Mexico in 1863 to protect French interests. It was on 30 April at Camerone Hacienda near Puebla that seventy Legionnaires were killed resisting 2,000 Mexicans for a day of heroic fighting. The name of the battle adorns every Legion flag. Following the defeat of the French by Prussia in1870, the Legion was then engaged at Tonkin and in North Africa. It suffered very heavy casualties in the First World War and the disbanded regiments were amalgamated into the Foreign Legion's Regiment de Marche.

In the 1920s and 1930s, regiments were next involved in Morocco and the Middle East. The Legion was involved throughout the Second World War with the battalion-strength 13e Demi-Brigade Legion Etranger (13th Foreign Half-Brigade/13DBLE) making a name in Norway and then, in 1942, at Bir-Hakeim in Libya. From 1945 to 1954, virtually the entire Legion was heavily involved in Indo-China until the surrender at Dien Bien Phu.

It then returned to Algeria and fought in a bitter war of independence in which 2,500 Legionnaires were killed. When Algeria was given its independence, General de Gaulle took his revenge for the Army's objections to this by axing the parachute divisions and demanded that every Legionnaire should be vetted.

The regiments were dispersed until a new home was found in Aubagne, Provence. More recently, units were involved in the Gulf War and former Yugoslavia.