On 14th August, 1914, the French Army, led by Ferdinand Foch, Auguste Dubail and Michel Maunoury attempted to capture Lorraine. Rupprecht and the Sixth Army successfully withstood the attack and persuaded Hermuth von Moltke, Chief of General Staff, to allow him to launch a major counter-offensive at the end of August. Rupprecht failed to breakthrough French defences and remained on the Western Front for the rest of the war.
In July 1916, Rupprecht was promoted to field marshal. Considered to be the most competent of the royal commanders, he clashed several times with the Chief of General Staff, Erich von Falkenhayn, who replaced Hermuth von Moltke. Revolutionary activity after the war deprived Rupprecht of his Bavarian throne. Prince Rupprecht lived in quiet retirement until his death in 1955.