The previous organisation had seen Australia raise three field brigades as part of the 1st Division, but under the reorganisation each division would also receive a howitzer brigade. These were numbered consecutively, starting from the 101st, with the 103rd being assigned to the 12th Howitzer Brigade. After their arrival in France in mid-1916, the artillery was reorganised again and the howitzer brigades were subsumed into the field brigades; consequently the 103rd became part of the 3rd Field Brigade in April, and were assigned to the 1st Division. They were initially equipped with four guns, but in January 1917 this was expanded to six. The battery was committed to the fighting a short time later, joining the 3rd Field Brigade's other units – the 7th and 8th Field Batteries – near the front line around Fleurbaix, about south-west of Armentieres, near the French–Belgian border. For the next two-and-a-half years they provided artillery support to the infantry fighting in the trenches along the front. Their time was punctuated by periods out of the line and further reorganisations such as the one that occurred in January 1917, when the 3rd Field Brigade was renamed the 3rd Field Artillery (Army) Brigade. After the armistice was signed in November 1918, the demobilisation process began and the battery's personnel were slowly repatriated to Australia. As its numbers dwindled, in February 1919, just before the unit's final cadre began their journey home, it was amalgamated with the 101st Howitzer Battery. During the inter-war years, the battery was reformed twice as part of the Citizen Forces. Initially, it was reformed in 1920 in Sydney, but the following year Australia's part-time military was reorganised to perpetuate the numerical designations and formations of the AIF, and the unit was disbanded and re-formed in Western Australia as part of the newly re-raised 3rd Field Brigade, which was headquartered at Guildford, Western Australia. In doing so, it drew personnel from the previously existing 38th and 39th Field Batteries. Throughout the inter-war years, the battery remained in this form until after the start of World War II. As a Militia formation, the 103rd Battery could not be deployed overseas to fight after the outbreak of the war, and while some of its members volunteered for service with the Second Australian Imperial Force it remained in Australia. In 1941, Australia's artillery formations were reorganised along regimental lines, equipped with two field batteries.