On the outbreak of the First World War, the regiment was sent to Persia in 1916, where it raised a second battalion later that year. The 2nd Battalion served with great gallantry in the Mesopotamian Campaign, where it fought in the Battles of Khudaira Bend, Jebel Hamrin and Tikrit. In 1918, it proceeded to Palestine and took part in the Battle of Megiddo, which led to the defeat of Turkish Army in Palestine. In the meantime, a third battalion was raised in 1917, which served in South Persia and later, in the Third Afghan War of 1919 and during the Arab uprising in Iraq in 1920. The 1st Battalion also served in the Third Afghan War. During the First World War, the three battalions of 124th DCO Baluchistan Infantry suffered a total of 1179 casualties including 459 killed or died of disease.