When World War I broke out, Agricola was mobilized along with his regiment, just a few days after the death of his father. Agricola served mostly at the Western front, and although he never received a troop command throughout the war (only staff assignments), this indicated that he was destined for a more ambitious career than most of his fellow troop officers; he became Adjutant of a battalion in his regiment on 2 August 1914, participated in the battle of the Marne in September and was promoted to "Oberleutnant" (First Lieutenant) in December. In early January 1915 he served as the regimental Adjutant of his pre–war regiment until August 1916, when he was temporarily elevated to Brigade Adjutant. In that capacity, he saw action at the Battle of the Somme, where he distinguished himself numerous times. On 9 January 1917 he was transferred to the staff of the 219th (10th Royal Saxon) Infantry Division, occupying a relatively quiet sector of the front line in Lorraine. A few weeks later, on 27 January, he was promoted to "Hauptmann" (Captain) and four days later, the last King of Saxony, Frederick Augustus III, bestowed him with one of Saxony's highest decorations, the Military Order of St. Henry, in recognition of his conduct during the battle of Somme the previous year. He received his last wartime assignment on 25 May 1917, when he was transferred to the staff of the XII (1st Royal Saxon) Corps.