The French Forces of the Interior (FFI; ) were
French resistance
The French Resistance ( ) was a collection of groups that fought the German military administration in occupied France during World War II, Nazi occupation and the Collaboration with Nazi Germany and Fascist Italy#France, collaborationist Vic ...
fighters in the later stages of
World War II
World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
.
Charles de Gaulle
Charles André Joseph Marie de Gaulle (22 November 18909 November 1970) was a French general and statesman who led the Free France, Free French Forces against Nazi Germany in World War II and chaired the Provisional Government of the French Re ...
used it as a formal name for the resistance fighters. The change in designation of these groups to FFI occurred as
France's status changed from that of an occupied nation to one of a nation being liberated by the
Allied armies. As regions of France
were liberated, the FFI were more formally organized into light infantry units and served as a valuable manpower addition to regular
Free French forces. In this role, the FFI units manned less active areas of the front lines, allowing regular French army units to practice
economy of force measures and mass their troops in decisive areas of the front. Finally, from October 1944 and with the greater part of
France liberated, the FFI units were amalgamated into the French regular forces
continuing the fight on the Western Front, thus ending the era of the French irregulars in World War II.
Liberation
After the
invasion of Normandy in June 1944, at the request of the
French Committee of National Liberation
French may refer to:
* Something of, from, or related to France
** French language, which originated in France
** French people, a nation and ethnic group
** French cuisine, cooking traditions and practices
Arts and media
* The French (band) ...
,
SHAEF placed about 200,000 resistance fighters under command of
General
A general officer is an Officer (armed forces), officer of high rank in the army, armies, and in some nations' air force, air and space forces, marines or naval infantry.
In some usages, the term "general officer" refers to a rank above colone ...
Marie Pierre Kœnig, who attempted to unify resistance efforts against the Germans. General
Eisenhower confirmed Koenig's command of the FFI on 23 June 1944.

The FFI were mostly composed of resistance fighters who used their own weapons, although many FFI units included former French soldiers. They used civilian clothing and wore an armband with the letters "F.F.I."
According to General
Patton, the rapid advance of his army through France would have been impossible without the fighting aid of the FFI. General
Patch estimated that from the time of the
Mediterranean landings to the arrival of U.S. troops at
Dijon
Dijon (, ; ; in Burgundian language (Oïl), Burgundian: ''Digion'') is a city in and the Prefectures in France, prefecture of the Côte-d'Or Departments of France, department and of the Bourgogne-Franche-Comté Regions of France, region in eas ...
, the help given to the operations by the FFI was equivalent to four full divisions.
FFI units seized bridges, began the liberation of villages and towns as Allied units neared, and collected intelligence on German units in the areas entered by the Allied forces, easing the Allied advance through France in August 1944. According to a volume of the U.S. official history of the war,
In Brittany, southern France, and the area of the Loire
The Loire ( , , ; ; ; ; ) is the longest river in France and the 171st longest in the world. With a length of , it drains , more than a fifth of France's land, while its average discharge is only half that of the Rhône.
It rises in the so ...
and Paris
Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, largest city of France. With an estimated population of 2,048,472 residents in January 2025 in an area of more than , Paris is the List of ci ...
, French Resistance forces greatly aided the pursuit to the Seine
The Seine ( , ) is a river in northern France. Its drainage basin is in the Paris Basin (a geological relative lowland) covering most of northern France. It rises at Source-Seine, northwest of Dijon in northeastern France in the Langres plat ...
in August. Specifically, they supported the Third Army in Brittany and the Seventh U.S. and First French Armies in the southern beachhead and the Rhône valley. In the advance to the Seine, the French Forces of the Interior helped protect the southern flank of the Third Army by interfering with enemy railroad and highway movements and enemy telecommunications, by developing open resistance on as wide a scale as possible, by providing tactical intelligence, by preserving installations of value to the Allied forces, and by mopping up bypassed enemy positions.
Political tension
On 20 June 1944 the French high command decreed that the mobilization requirements dating from the start of the war remained in effect, that the FFI units would become part of the French Army, and that the FFI was subject to French military law. After the
liberation of Paris in August 1944, Charles de Gaulle almost immediately confronted a challenge to his authority from an FFI flush with triumph as towns and cities were liberated in the wake of the German retreat from France. In late August 1944 incidents of FFI misbehavior occurred in the region of Paris, highlighting the risks of having an armed and organized citizenry that suddenly found itself without a mission. De Gaulle believed France required a single decisive
leader
Leadership, is defined as the ability of an individual, group, or organization to "", influence, or guide other individuals, teams, or organizations.
"Leadership" is a contested term. Specialist literature debates various viewpoints on the co ...
to restore effective government. The FFI believed they should have a share in national power because of their contribution to the Allied war-effort. Subsequently, de Gaulle declared the FFI would be either disbanded or integrated into the
French Army
The French Army, officially known as the Land Army (, , ), is the principal Army, land warfare force of France, and the largest component of the French Armed Forces; it is responsible to the Government of France, alongside the French Navy, Fren ...
, and a series of tense meetings between de Gaulle and FFI leaders in major cities ensued. Despite FFI disenchantment with de Gaulle's methods, in large part they accepted his decision that FFI members would either be amalgamated into the French regular army or return to civilian life.
Amalgamation

Subsequent to the liberation of areas where FFI units operated, they often formed battalions and brigades named for their commanders or region of origin (Battalion Oziol, etc.) These FFI units were predominantly of the
light infantry
Light infantry refers to certain types of lightly equipped infantry throughout history. They have a more mobile or fluid function than other types of infantry, such as heavy infantry or line infantry. Historically, light infantry often fought ...
class, although some formed light
reconnaissance
In military operations, military reconnaissance () or scouting is the exploration of an area by military forces to obtain information about enemy forces, the terrain, and civil activities in the area of operations. In military jargon, reconnai ...
units like the 12th Regiment of Dragoons. Some of these units were used to besiege German troops in still-occupied French ports or to secure France's alpine frontier with Italy, others were used to secure Allied lines of communications in France, and still others were assigned as army reserve units for the use of
General
A general officer is an Officer (armed forces), officer of high rank in the army, armies, and in some nations' air force, air and space forces, marines or naval infantry.
In some usages, the term "general officer" refers to a rank above colone ...
de Lattre de Tassigny's
French First Army. From October 1944 until March 1945, the FFI units were amalgamated into the French Army in order to regularize the units. Units such as the 49th Infantry Regiment (formerly the FFI
Corps Franc Pommiés) and the 3rd Demi-Brigade of Chasseurs (formerly the FFI
Alsace-Lorraine Brigade) were constituted in this manner using FFI manpower. Amalgamation was successful in varying degree; the training, tactics and attitudes of the former
French Resistance
The French Resistance ( ) was a collection of groups that fought the German military administration in occupied France during World War II, Nazi occupation and the Collaboration with Nazi Germany and Fascist Italy#France, collaborationist Vic ...
fighters often differed from those of the regular soldiers with whom they served. General De Lattre's comments on this situation are enlightening:
raditional military valueswere not and could not be the characteristics of the F.F.I. units. Condemned to be born and live in secret, placed outside the law by the enemy and by the enemy's accomplices, they had above all developed the revolutionary military virtues, those of partisans. By force of circumstances the personalities of the leaders had played a determining role and had stamped each maquis with a different brand.
. . .
To the regiments we had landed the extreme variety of the F.F.I. organizations, their at least peculiar discipline, the differing quality of their groups, the poverty of their equipment, the crying inadequacy of their armament and supplies, the heterogeneity of their officering, the facility with which their superior ranks had been assigned, and in certain cases the ostensibly political nature of their aims, ran counter to the classical military outlook of many officers, some of whom, in reaction, exaggerated their regulation strictness.
. . .
The part he FFIhad taken in the fight for liberation not only encouraged them rightly in the wish to retain their individuality; their successes, valued often from a local angle, established in their view the excellence of the military system which circumstances had led them to create and which they intended to substitute for the traditional system, which they considered out-of-date.
A total of 68 infantry regiments and half-brigades, two special forces battalions, 20 light infantry or reconnaissance battalions, one tank battalion, sixteen artillery regiments, two anti-aircraft artillery regiments, five engineer regiments, and three construction regiments were ultimately formed from FFI manpower by the close of 1945.
Weapons and equipment
The weapons and equipment of the FFI were highly varied. For example, the
Royal Air Force
The Royal Air Force (RAF) is the Air force, air and space force of the United Kingdom, British Overseas Territories and Crown Dependencies. It was formed towards the end of the World War I, First World War on 1 April 1918, on the merger of t ...
(working alongside the
Special Operations Executive
Special Operations Executive (SOE) was a British organisation formed in 1940 to conduct espionage, sabotage and reconnaissance in German-occupied Europe and to aid local Resistance during World War II, resistance movements during World War II. ...
) parachute-dropped British-made weapons such as
Sten guns, revolvers, grenades and explosives to the FFI in order to harass German forces. This enabled the FFI to capture German weaponry which was also used.
Because they were not units that the United States had formally agreed to logistically support, they were not eligible to receive the standard U.S. equipment that was provided to French regular army units. Thus, the FFI units often clothed themselves in nonstandard uniforms or uniforms of 1940 vintage. The same condition existed with weapons, with the use of captured German infantry weapons a common practice. Because of the mix of American, British, French, German, and other weapons, the supply of ammunition and spare parts was complicated and often difficult to accomplish. By no means unique in the diversity of its armament, the 34th Infantry Regiment (formed on 1 January 1945) possessed the following weapons in August 1945: 1,760 (German)
Mauser rifles, 470 (British)
Sten sub-machine guns, 108 German sub-machine guns, 27 (French)
Hotchkiss machine guns, 33 50-mm mortars and 12 81-mm
mortars, two 20-mm cannon, and three 25-mm cannon. The soldiers' uniforms were described as second-hand and of diverse origins.
Some heavy armored fighting vehicles were obtained, notably British
Cromwell tanks (150 provided by the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...
) and captured German tanks (44, of which 12 were
Panthers). The 12th Regiment of Dragoons received 12
Cavalier tanks among other British equipment in April 1945. In other cases, FFI units used vehicles no longer favored by Allied forces, such as the U.S.
M6 Fargo, a light truck with a
portee 37 mm
antitank gun. Finally, civilian vehicles and practically anything else in running condition were pressed into service and used until they could no longer be maintained.
French strategic asset
As regions of
France were liberated, the FFI provided a ready pool of semi-trained manpower with which France could rebuild the French Army. Estimated to have a strength of 100,000 in June 1944, the strength of the FFI grew rapidly, doubling by July 1944, and reaching 400,000 by October 1944.
According to the
Defence Historical Service (SHD), 252,000 individuals have been approved as FFI.
Although the amalgamation of the FFI was in some cases fraught with political difficulty, it was ultimately successful and allowed France to re-establish a reasonably large army of 1.3 million men by
VE Day.
[Vernet, J. ''Le réarmement et la réorganisation de l'armée de terre Française (1943–1946)'', pages 86 and 89. Ministere de la Defense, Château de Vincennes, 1980. Vernet lists 10 divisions that were formed with FFI manpower. Ultimately, some 103 light infantry battalions and six labor battalions were formed with FFI personnel prior to VE Day.]
See also
* ''
Binnenlandse Strijdkrachten'' (Netherlands)
*
French Liberation Army
Citations
{{Authority control
Military history of France during World War II
France
France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...
French Resistance networks and movements