Marching regiment

A regiment de marche (roughly 'marching regiment' in English) is a French temporary (provisional not permanent), regiment created for a specific campaign or other military purpose. 
Clayton describes a "batallion de marche" as comprising the 'fit trained personnel' of all the battalions from a two to three battalion regiment. This creation of a provisional unit may be undertaken because of manpower shortages on mobilisation if new drafts of conscripts and volunteers had not yet arrived.
Marching battalions may also be created from:
Other designations used are marching battalions () or Marching Squadrons (), or marching brigades comprising several regiments. 
History.
The concept of marching units was used throughout the 19th and 20th centuries in the French Army and its associated military systems.
Under the First French Empire, the designation of Provisional Regiment was used to identify a regiment created by levies from different regular units, or from garrison troops. In the 20th century however only the term "regiment de marche" continued to be used.
Early "Unites de marche" of the French Army.
The first marching regiments appeared during the Napoleonic Wars. The Spanish War () saw heavy casualties amongst the regular French units involved and in 1808 Napoleon I authorised the creation of marching regiments to replace these losses. 
Napoleon I designated "provisional regiments" for specific assignments as well as "marching regiments" intended for deployment outside France. These ad hoc units might also be used to bring metropolitan garrisons up to strength. 
It was in 1812, during the Russian Campaign (), that the concept of marching regiments became general.
As examples:
During the retreat from Moscow, marching regiments were constituted to bring back scattered detachments from fragmented corps to their respective units of origin. 
Spanish expedition and siege of Algiers.
During the Spanish Expedition () in April 1832, a number of depot units were sent to Spain under the designation of Provisionary Regiments 
Later, during the expedition of 1830 and the siege of Algiers (), Marching Regiments were created and embarked. Général Étienne Alexandre Bardin () explained in his "Dictionary of the French Army" that these marching regiments were used because the under strength light infantry units could only provide two formed battalions of veteran chasseurs. 
During this period, opinions differed in respect of the effectiveness of employing marching regiments. The administrator Pierre Agathange Audier recommended the practice in his "Study course of military administration" published in 1824. However, Général Étienne Alexandre Bardin expressed the contrary view that "If in the course of a major war and during distant operations we are forced to resort to this method of reinforcing the army, the practice is administratively deplorable".
Overseas and foreign campaigns of the Second French Empire.
Expeditions undertaken in Algeria, Russia, Mexico and Italy during the Second French Empire made use of marching regiments.
Crimean War.
Marching regiments drawn from units of the French Army of Africa were engaged from 1854 to 1856 in the Crimean War.
French intervention in Mexico.
The French expeditionary corps which disembarked in Mexico () on 8 January 1862 consisted initially of the "1st Marching Regiment" plus 2,000 men of the 1st Marine Infantry Regiment (1erRIMa) and the 2nd Marine Infantry Regiment (2e RIMa).
The same year, reinforcements were received from the "2nd Marching Cavalry Regiment" (Lieutenant-Colonel Jean-Auguste Margueritte), which was composed of two squadrons drawn from the "12th Chasseurs à Cheval Regiment" plus two squadrons taken from the "3rd African Chasseurs Regiment".
Franco-German war of 1870.
The disaster of the Franco-Prussian War () led the French to create in urgency numerous marching regiments. 
End of the Second French Empire.
The "13th Army Corps" () (général Vinoy () was formed in August 1870 at Paris. The Marching Regiments of this corps were constituted of three depot battalions belonging to different regiments with recruits or recalled veteran soldiers.
Beginning of the Third French Republic.
Siege of Paris.
Following the disaster of Sedan (), a national defense government () proclaimed on 4 September 1870 the Third French Republic and the decline of Emperor Napoleon III (). The 14th Army Corps (général Renault ()) was formed accordingly in the entrenched camp of Paris. The battalions in depot had already deployed, and the only available units left were a company of each deployed regiment, in charge of receiving soldiers recalled for service. Accordingly, the available companies were doubled. These demi-companies were supposed to form the regiment of the 14th Corps. Each new regiment accordingly consisted of eighteen different company corps. 
Excluding these two army corps, a "Zouaves Marching Regiment" was formed from divers units, the "28th Marching Regiment" () with the depot of the Imperial Guard of the Second Empire (), the "36th Marching Regiment" (), the "37th Marching Regiment" (), the "38th Marching Regiment" (), and the "39th Marching Regiment" () with the depots which remained in Paris.
Army of the East.
In December 1870, the different army corps of the Army of the east () of général de division Bourbaki were reinforced by marching regiments. 
The "15th Army Corps" of général de division Martineau des Chenez received:
The "18th Army Corps" of général de division Billot received:
The "20th Army Corps" of général de division Clinchant received:
The "24th Army Corps" of général de division Bressolles received:
The "General Reserve" of French Navy Capitaine de frigate Pallu de la Barrière () received: 
World War I.
Less than a year from the beginning of first world war, the government decided on 25 January 1912, to constitute 40 Marching Battalions, as in 2 Marching Battalion by military region. They were formed of new recruits, reserve soldiers in the depot of garrisons and the wounded medically refit for service. 
Marching Regiments were equally created from the troupes d'Afrique (), such as the 4th Marching Tirailleurs Regiment. 
The 1st Foreign Regiment 1er RE of Sidi Bel-Abbès and the 2nd Foreign Regiment 2e RE of Saida, garrisoned in Algeria, mounted four demi-battalions destined constitute the principal formations of the future regiments:
The Marching Regiment of the Foreign Legion (RMLE) was created on 11 November 1915 by fusion of the 2nd Marching Regiment of the 1st Foreign Regiment (2eRM 1erRE) and the 2nd Marching Regiment of the 2nd Foreign Regiment (2eRM 2e RE). The "Marching Regiment" participated to Battle of the Somme () in 1916 and to Second Battle of the Marne () in 1918.
Whilst the Foreign Legion's battalions de marche are the most renowned in WW1, other troop types were similarly grouped, such as the "1er Régiment de Marche d’Infanterie Colonial du Maroc" associated with the Moroccan Division (France). In Palestine, the Détachement Français de Palestine et de Syrie comprised such a regiment of Tirailleurs Algériens and of Armenian volunteers in the Légion d'Orient.
The first "Régiment de Marche d’Afrique" was made up of two troop types of the Armée d'Afrique, its first two battalions formed of Zouaves and its third of Foreign Legionnaires. The second regiment was formed solely of Zouaves. Both units were in the Corps expéditionnaire d'Orient and saw combat in the Gallipoli campaign.
World War II.
On the outbreak of World War II in September 1939, a "Marching Regiment" was constituted from the three battalions of the "146th Fortress Infantry Regiment" (), the "156th Fortress Infantry Regiment" (), and the "160th Fortress Infantry Regiment" (), to participate in the Saar Offensive (). This "Marching Regiment" penetrated Germany through the woods of Warndt, then received an order to retreat following the capitulation of Poland. 
At the same time, Marching Regiments of the French Foreign Legion were constituted to gather foreigners wishing to serve in the French Army. Accordingly, 5,000 Ukrainian volunteers who did not want to serve in either the Polish or Soviet forces, enlisted in the 21st, 22nd and 23rd Marching Regiments of Foreign Volunteers (RMVE).
Following the Armistice of 22 June 1940 (), the African units which rallied to Free France () were organized by général de Gaulle in "Marching Battalions" principally in the 1st Free French Division (). The 1st Marching Regiment of Moroccan Spahis (), created on 24 September 1942, was the first "Marching Regiment" of Free France. The "Marching Regiment of Tchad", created in July 1943 from the Senegalese Tirailleurs of Tchad, was the first "Regiment" of Free France, and illustrated capability at Kufra () until Germany. Due to these "Faits d'armes", this regiment was the only marching regiment which was not dissolved after the Liberation and which still is active under the respective designation. 
From 1 July 1943 until 1 July 1945, the 3rd Foreign Infantry Regiment 3e REI had been designated as Marching Regiment of the Foreign Legion (RMLE) which was the original designation for the latter from 15 November 1915 until 15 November 1920.
First Indochina War.
In May 1945, the French Foreign Legion started the creation of a régiment de marche to be sent to re-occupy Indochina; their training and administrative base at Sidi-bel-Abbès, sixty miles south of Oran in northwest Algeria. During the Indochina war, the Legion's strength would reach 30,000 men.
Other armies Marching Units.
Austria-Hungary.
The Austro-Hungarian Army made use of "marching units" during World War I. The "Marching Battalions" were regrouped in "Marching Regiments", and two marching regiments formed the "Marching Brigade".
Germany.
Grand Duchy of Baden.
In 1808 the Grand Duchy of Baden, created in 1806 under the impulsion of Napoleon I, contributed a "combined infantry regiment" for service alongside the French in the Peninsular War. In 1809 it became the "Linien-Infantry-Regiment N°4".
Electorate of Bavaria.
During the Battle of Hohenlinden in December 1800 the Bavarian Corps, serving alongside the Austro-Hungarian Army against the French, had a "Combined Light Horse Regiment" consisting of six squadrons. Such was one of the first appearances of this type of regiment. 
Kingdom of Prussia.
In 1812, the auxiliary corps of the Kingdom of Prussia was essentially formed of "combined regiments" composed of battalions or squadrons issued from the different regiments. 
Once peace prevailed again, Prussia continued deploying combined regiments during grand maneuvers. Accordingly, during the grand maneuvers of Kalisch, which took place during the summer of 1835 the Russian and Prussian Army, the latter having contributed two "combined cavalry regiment" and a "combined infantry regiment". 
In 1859 and 1860 a new short-lived form of combined regiments was created. Those were Landwehr regiments augmented by mobilized reserve troops and reserve formations, named "Combined Infantry Regiment". In 1860 they were converted into regular infantry regiments.
German Empire.
During World War I the German Imperial Army formed marching regiments from various incomplete units and detached elements; like the "79.R/85.L" which was formed with the staff and four companies of the 79th Reserve Infantry Regiment and two battalions of the 85th Landwehr Regiment.
German Reich.
During World War II the Wehrmacht used the term "Kampfgruppe" for ad hoc formations; usually with combined arms and anywhere from companies to a full corps in size.
Russia.
In October 1813, during the Battle of Leipzig, the Russian reserve Army of Poland commanded by Levin August von Bennigsen consisted of "2nd Combined Regiments of Uhlan" comprising four squadrons. 
In the years of 1830, the Imperial Russian Army had taken the habit of creating "Combined Regiments", formed of various regular units, to participate to grand-maneuvers. During the Grand-Maneuvers of Kalisch, which united in 1835 the Prussian Army and Russia Army, Russian Imperial Guard placed in lieu a "combined cavalry regiment" and a "combined infantry regiment".