The Legion was primarily used 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 and both World Wars. The Foreign Legion has remained an important part of the French Army, 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 French loss of the legion's base, Algeria.
Membership of the Legion is often a reflection of political shifts: specific national representations generally surge whenever a country has a political crisis and tend to subside once the crisis is over and the flow of recruits dries up. After the First World War, many (Tsarist) Russians joined. Immediately before the Second World War, Czechs, Poles and Jews from Eastern Europe fled to France and ended up enlisting in the Legion.
Following the break-up of Yugoslavia, there were many Serbian nationals. Also in the 1990s, the collapse of the Soviet Union, and the changes in the former Warsaw Pact countries, led to an increase in recruitment from Poland and from the former republics of the USSR (If you're interested in joining, click here!).