Upon reporting to General John Joseph "Blackjack" Pershing, Commander-in-chief (CinC) of the American Expeditionary Force (AEF) on the Western Front, he was assigned to command a brigade of the 32nd Division but later assumed command of the 4th Marine Brigade, part of the 2nd Division, immediately following the attack of the division in the Battle of Soissons. On July 28, 1918, Major General Lejeune assumed command of the 2nd Division and remained in that capacity until August 1919, when the division was demobilized 9 months after the end of the war. He was the second Marine officer to hold an Army divisional command (Marine Brigadier General Charles A. Doyen had previously commanded the division for two weeks), and following the Armistice with Germany in November 1918 he led his division in the march into Germany.