the first army was reconstituted as the french army b under the command of general jean de lattre de tassigny in the summer of 1944. it landed in southern france after operation dragoon, the allied invasion of the area. on 25 september 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 (also known as the u.s. sixth army group) 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 january 1945 it defended against operation "nordwind", the last major german offensive on the western front. 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. armee 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.