First Army ( France ) The First Army ( ) was a field army of France that fought during World War I and World War II . It was also active during the Cold War . First World War . On mobilization in August 1914 the First Army was put in the charge of General Auguste Dubail and comprised the 7th , 8th , 13th , 14th , and 21st Army Corps , two divisions of cavalry and one reserve infantry division . It was massed between Belfort and the general line Mirecourt - Lunéville with headquarters at Epinal . First Army then took part , along with the French Second Army , in the Invasion of Lorraine . The First Army intended to take the strongly defended town of Sarrebourg . German Crown Prince Rupprecht , commander of the German Sixth Army , was tasked with stopping the French invasion . The French attack was repulsed by Rupprecht and his stratagem of pretending to retreat and then strongly attacking back . On August 20 , Rupprecht launched a major counter - offensive , driving the French armies out . Dubail was replaced in 1915 . A frantic 1916 saw four different commanders command the First Army ; an even more frantic 1917 saw five different commanders at the helm ( including François Anthoine during the Battle of Passchendaele ) . Composition . At the time of the Battle of Passchendaele , the First Army was composed of two corps - the 1st Army Corps ( composed of 4 divisions ) and the 36th Army Corps ( composed of 2 divisions ) . Second World War . 1940 . During World War II the Army under the command of General Georges Blanchard formed part of the forces ranged against the German Army during the Battle of France . On 10 May 1940 , it included the Cavalry Corps , 3rd Army Corps , 4th Army Corps , the 5th Army Corps , as well as the " 1re Division Cuirassée de Réserve " ( 1st DCR , effectively an armoured division with four battalions of tanks and one of infantry , plus supporting units ) and 32nd Infantry Division . When the Wehrmacht invaded France and the Low Countries in 1940 , the First Army was one of the many armies including the British Expeditionary Force ( BEF ) that advanced north to stop the German armies . On May 21 , 1940 , the First Army was one of the armies trapped in a vast pocket with their backs to the sea that would eventually result in the Dunkirk evacuations . As the Germans moved in , what remained of the once - formidable First Army was hopelessly surrounded at Lille . It is estimated that the First Army ' s last battle allowed the evacuation of an additional 100 , 000 men from Dunkirk . The First Army formally ceased to exist on May 29 , though a portion escaped with the British troops . 1944 - 1945 . French Army B under the command of General Jean de Lattre de Tassigny landed in southern France after Operation Dragoon , the Allied invasion of the area . On September 25 , 1944 French Army B was redesignated French First Army . Liberating Marseilles , Toulon , and Lyon , it later formed the right flank of the Allied Southern Group of Armies at the southern end of the Allied front line , adjacent to Switzerland . It commanded two corps , the French I and II Corps . The French First Army liberated the southern area of the Vosges Mountains , including Belfort . Its operations in the area of Burnhaupt destroyed the German " IV Luftwaffe Korps " in November 1944 . In February 1945 , with the assistance of the U . S . XXI Corps , the First Army collapsed the Colmar Pocket and cleared the west bank of the Rhine River of Germans in the area south of Strasbourg . In March 1945 , the First Army fought through the Siegfried Line fortifications in the Bienwald Forest near Lauterbourg . Subsequently , the First Army crossed the Rhine near Speyer and captured Karlsruhe and Stuttgart . Operations by the First Army in April 1945 encircled and captured the German " XVIII S . S . Korps " in the Black Forest and cleared southwestern Germany . At the end of the war , the motto of the French First Army was " Rhin et Danube " , referring to the two great German rivers that it had reached and crossed during its combat operations . Composition . The First Army was mainly composed of North African units ( Maghrebi s and French Pied - noirs soldiers ) from the Army of Africa which already played a major role in the liberation of Corsica ( September - October 1943 ) and the Italian Campaign ( 1943 – 44 ) in which around 130 , 000 of their force ' s men engaged . During the French and German campaigns of 1944 - 45 these units formed the core of the First Army which comprised about 260 , 000 men ( including 50 % Maghrebis ) , and eventually more than 320 , 000 men during its offensive advances in Germany and in Austria , From 26 September 1944 André Malraux ' s Alsace - Lorraine Independent Brigade , formed from the FFI , formed part of the army ' s reserves . Like other units formed from FFI personnel , Malraux ' s brigade was subsequently incorporated as a regular unit ( and was retitled the 3rd Demi - Brigade of Chasseurs ) into the French Army . Postwar . During the Cold War the First Army was again active , controlling the I Corps , the II Corps , and the III Corps as well as Army troops , including Pluton artillery , during the 1980s . After deactivation as the war HQ for the Central Army Group , Ouvrage Rochonvillers was designated as the First Army ' s war headquarters in the 1980s .