List of military legions

This list of military legions is in chronological order where possible. In modern times, most units using the name "military legions" were composed of soldiers from a specific ethnic, national, religious or ideological background, and that background is often specified in the legion's name. Since the Napoleonic Wars, many countries have used the term "legionnaire" to refer to recruits who are neither citizens nor imperial subjects of the government whose military they enter. These governments often, but do not always, group these foreign recruits into specific units that bear the name "legion."

Ancient Rome

 * List of Roman legions
 * Theban Legion, a Roman legion whose members, according to a long-lasting tradition, were massacred for their Christian beliefs

18th century

 * Western Legion and Eastern Legion, Greek rebel forces under Russian command in the Orlov Revolt (1770)
 * Lee's Legion (1776–83), an infantry and cavalry unit of the American Continental Army
 * Armand's Legion (1778–83), an American dragoon unit
 * British Legion (American Revolution) (1778–83), made up of Loyalist American infantry and cavalry
 * Lauzun's Legion (1778–82), a composite corps of the French Army comprising cavalry, infantry and artillery elements, mostly recruited from foreign mercenaries
 * Jamaica Legion, fighting on the British side in the American War of Independence, involved in the San Juan Expedition (1780).
 * Pulaski's Legion (1778–80), one of the few cavalry regiments in the American Continental Army, later merged into Armand's Legion
 * Legion of the United States (1792–96), an early United States land force commanded by Anthony Wayne
 * French Revolutionary Legion of the Mississippi, a French commissioned force of Americans commanded by George Rogers Clark

French Revolutionary and Napoleonic Wars

 * Légion des Allobroges, Swiss, Piedmontese, and Savoyard supporters of the French Revolution
 * Batavian Legion, Dutch supporters of the French Revolution in 1793
 * Belgian Legion (1792), Liégeois Legion, and Legion of Belgians and Liégeois: Belgian volunteers fighting on the side of the Republicans in the French Revolution
 * Irish Legion, a French battalion established in 1803 for a future invasion of Ireland
 * King's German Legion, British units of expatriate German personnel that fought against the French during the Napoleonic Wars
 * La Legion Noire (The Black Legion), a military unit of the French Revolutionary Army
 * Polish Legions (Napoleonic period), Polish units in the service of Napoleonic France
 * Russian–German Legion, Germans (as well as Dutch and Belgians) in the service of Tsarist Russia

19th century

 * Belgian Legion, the name of several units of Belgian volunteers who fought in various 19th century conflicts
 * British Legions, foreign volunteer units, established in 1819, who fought against Spain in South America's independence wars
 * British German Legion, a group of German soldiers recruited to fight for Britain in the Crimean War, 1855–1856
 * Greek Legion (Septinsular Republic), a Septinsular Republic unit active between 1805 and 1807, taking part in the War of the Third Coalition and the Russo-Turkish War (1806–1812)
 * Royal Foreign Legion (Légion royal étrangère), infantry corps of mostly German mercenaries forming part of the restored French Bourbon army in 1815, renamed the Hohenlohe Regiment after 1821
 * British Legion (1835), officially the Auxiliary Legion, a British military force sent to Spain to support the Liberals and Queen Isabella II against the Carlists in the First Carlist War
 * Italian Legion, commanded by Garibaldi in the Uruguayan Civil War
 * Academic Legion (Vienna), a revolutionary students' group in Vienna in 1848
 * Academic Legion (Lviv), Polish nationalist students at the University of Lviv in 1848
 * Greek Volunteer Legion, helping Russia in the Crimean War
 * International Legion, a military force formed by Garibaldi in 1860 during the wars of Italian unification
 * The British Legion (1860) British contingent of the above
 * Nauvoo Legion, a significant militia in early Mormon history
 * List of American Civil War legions, both Confederate and Union
 * Guelphic Legion, Hanoverian paramilitary unit supporting George V, deposed king of Hanover, from 1866 to 1870
 * Carabinieri legions, the regional units of the Italian gendarmerie, established following the unification of the country.

World War I

 * Czechoslovak Legions, Czech and Slovak volunteer forces fighting on the Allied Powers side
 * French Armenian Legion, part of the French Army; also involved in the Franco-Turkish War of 1918–21
 * Georgian Legion (1914–1918), a unit of the German Army recruited from Georgians
 * Infantry Regiment of the Academic Legion, formed by volunteer Polish students in 1918, later taken into the regular Polish Army
 * Italian Legione Redenta, an Italian military formation that participated in the Siberian Intervention during the Russian Civil War
 * Jewish Legion, in the British Army at Gallipoli and Palestine
 * Polish Legion in Finland, fighting for the Finns against the Russians
 * Polish Legions in World War I, part of the Austro-Hungarian Army
 * Puławy Legion, a Polish formation that was part of the Imperial Russian Army
 * Legion of Ukrainian Sich Riflemen, a corps of the Austro-Hungarian Army

Interwar period

 * 2nd Legions Infantry Division (Poland), elite unite of the Polish Army, mostly composed of veterans of the Polish Legions in World War I
 * Condor Legion, a unit of "volunteers" from the German Luftwaffe serving with the Nationalists during the Spanish Civil War
 * British Legion Volunteer Police Force, a short-lived police force established in response to the outcome of the Munich Agreement in September 1938
 * Aviazione Legionaria, Italian air force in the Spanish Civil War

World War II
Note: Except for the above, all World War II legions fought on the German side.
 * Czechoslovak Legion opposing the Germans in Poland, 1939
 * Free Arabian Legion, Arab volunteers, notably from Iraq, and North Africa fighting on the German side.
 * Armenian or Armenische Legion, name given to the 812th Armenian Battalion of the German Army, made up largely of Armenian Red Army prisoners of war
 * (Azerbaijan legion), made up largely of Azerbaijani Red Army prisoners of war
 * Blue Legion, Spanish volunteers fighting against the Soviet Union on the Eastern Front
 * Crna Legija (Black Legion), the name given to the 1st and 5th Croatian Ustaše Brigades
 * Croatian Legion
 * Croatian Air Force Legion
 * Croatian Anti-Aircraft Legion
 * Croatian Naval Legion
 * Estonian Legion, a unit in the Waffen SS created in 1942, mainly consisting of Estonian soldiers
 * Flemish Legion (Dutch: Vlaams Legioen), recruited among Dutch-speaking volunteers from German-occupied Belgium, notably from Flanders.
 * Walloon Legion (French: Légion Wallonie), recruited among French-speaking volunteers from German-occupied Belgium.
 * Légion française des combattants (French Legion of Fighters), a pro-Nazi Vichy French unit
 * Legion of French Volunteers Against Bolshevism (LVF), pro-Nazi French
 * Georgian Legion (1941–1945), a unit of the German army recruited from Georgians
 * Indische Legion, also known as the Free India Legion or Tiger Legion, an Indian unit raised in 1941 and attached to the German Army
 * Latvian Legion, a formation of the Waffen-SS created in 1943 and consisting primarily of ethnic Latvians
 * Legion of St. George, the original name of the British Free Corps
 * Ostlegionen (literally "Eastern Legions"), conscripts and volunteers from the occupied eastern territories recruited into the German Army
 * La Légion Tricolore, a pro-Nazi French unit which was absorbed into the LVF after six months
 * Volga Tatar Legion, one of several units formed by the Wehrmacht out of Soviet prisoners of war according to their ethnicity

Other

 * Arab Legion (al-Jaysh al-Arabī) (1920–56), the regular army of Transjordan, predecessor of the present Jordanian Army
 * Foreign legion (disambiguation)
 * French Foreign Legion, a unit of the French Army mainly composed of foreigners wishing to fight for France (1831–present)
 * Polish Legions (disambiguation), eleven units at different times between the 18th and 20th centuries (some of which are listed separately above)
 * Spanish Legion, an elite unit of the Spanish Army (1920–present)

21st century

 * International Legion of Territorial Defence of Ukraine, a volunteer foreign legion military unit created by the Government of Ukraine to fight in the 2022 Russian invasion of Ukraine