After the outbreak of World War I in July 1914, Rupprecht took command (2 August 1914) of the German Sixth Army in Lorraine. While much of the German army participated in the Schlieffen plan, the Crown Prince led his troops in the Battle of Lorraine (14 to 25 August 1914). His appointment to command the Sixth Army came as a result of his royal position, but the level of study he had performed before he took command was a factor behind his successful direction of the Sixth Army, and he proved a highly able commander. Rupprecht's army gave way to the French attack in August 1914, in the Battle of Lorraine, and then launched a counteroffensive on 20 August. Rupprecht failed to break through the French lines. In fact he was ordered by German General Staff to only occupy the French forces in that region. It was his idea to attack more aggressively. He later commanded the 6th Army in Northern France (until August 1916), and remained on the Western Front during the stalemate that would last until the end of the war. Only a few days after the battle, his oldest son, Luitpold, died of polio in Munich (27 August 1914).