1st Wilts served with the 25th Division until was transferred on 21 June 1918. On 21 June 1918, the 1st Wilts joined the 110th Brigade, part of the 21st Division, with which it served for the rest of the war. At the outbreak of war, the 2nd Wilts was serving as part of the Gibraltar Garrison. Recalled home to Britain, the 2nd Wilts was attached to the 21st Brigade, part of the 7th Division. As part of the 21st Brigade, the 2nd Wilts arrived in France in October 1914, in time to take part in the First Ypres, where it suffered heavy casualties in helping to stop the German advance. In December 1915, the 21st Brigade transferred to the 30th Division. In three years of action on the Western Front, the 2nd Wilts took part in most of the major engagements, including the battles of Neuve Chapelle, Aubers, Loos, Albert, Arras and Third Ypres. In March 1918 the 2nd Wilts, like the 1st Wilts, was nearly destroyed during the German Army's Spring Offensive, losing 22 officers and 600 men. In May 1918, the 2nd Wilts received orders to join the 58th Brigade, part of the 19th (Western) Division. As part of the 19th Division, the 2nd Wilts would see action with the division through the Hundred Days Offensive. In 1919, with the division's disbandment, the 2nd Wilts returned to its pre-war duties of policing the British Empire. Territorial Force and Special Reserve Under the pre-war British Army system, created during the Haldane Reforms, each regiment, in addition to having two regular battalions would have two reserve formations associated with it. One would be special reserve battalion, while the other would be the Territorial Force units. In the case of the Wiltshire Regiment, the 3rd Battalion was the special reserve formation. The 3rd Wilts came into active service during 1914. It would remain in the home islands throughout the war. For most of the war, it would act as the depot and training unit for the battalions of the Wiltshire Regiment. In 1917, it moved from the depot at Devizes to join the Portland Garrison in 1915. In 1917, the 3rd Wiltshires would be transferred to the Thames and Medway garrison. During the war, the Wiltshire's Territorial component would expand from one battalion to three. The 1/4th Wilts was called into service in 1914 as part of the South Western Brigade