The French Foreign Legion was created by Louis Philippe, the King of the French, on 10 March 1831 from the foreign regiments of the Kingdom of France. Recruits included soldiers from the recently disbanded Swiss and German foreign regiments of the Bourbon monarchy. The Royal Ordinance for the establishment of the new regiment specified that the foreigners recruited could only serve outside France. The French expeditionary force that had occupied Algiers in 1830 was in need of reinforcements and the Legion was accordingly transferred by sea in detachments from Toulon to Algeria.

The Foreign Legion was primarily used, as part of the Armée d'Afrique, to protect and expand the French colonial empire during the 19th century, but it also fought in almost all French wars including the Franco-Prussian War, World War I and World War II. The Foreign Legion has remained an important part of the French Army and sea transport protected by the French Navy, surviving three Republics, the Second French Empire, two World Wars, the rise and fall of mass conscript armies, the dismantling of the French colonial empire, and the loss of the Foreign Legion's base, Algeria.

More Info: en.wikipedia.org