At Virton in the Ardennes in August 1914 he commanded VI Corps, part of Ruffey’s Third Army. VI Corps was strengthened with an extra (third) infantry division, and faced German VI Reserve Corps. Sarrail's was the only corps of Ruffey’s Third Army to withstand the strong German counterattacks (the others being Brochin’s V Corps and Victor-Rene Broelle’s IV Corps). It was eventually forced to fall back to avoid encirclement. Sarrail told 42nd Division, which formed the rearguard, "you have given proof of "cran" (guts)".