When World War I broke out, Lukachich von Somorja served in the campaign against Serbia, where he distinguished himself as a competent commander. Lukachich von Somorja also fought at the Battle of Drina and the Italian front of the war. On , he was promoted to major general. In November 1916 he was transferred to the Russian front. Later in the same year, he was selected to lead the 20th Landwehr Division, and returned to the Italian front in August 1917. He fought at the Battle of Doberdò and seven of the Battles of the Isonzo. At the Eleventh Battle of the Isonzo, he fought valiantly while commanding the 20th Landwehr Division. This earned him the Officer's Gold Knight's Medal. He went on to fight at the Battle of Caporetto. On , Lukachich von Somorja was awarded the Order of Maria Theresia, and with it the title of Baron of Somorja. During the early days of 1918, he was put in charge of many garrisons throughout Hungary and promoted to Feldmarschalleutnant on .