On 1 August 1914, France decreed a general mobilisation of its armed forces. A total of 145 territorial infantry regiments were formed at the start of hostilities. In addition, the Territorial Army formed cavalry squadrons, artillery groups, engineering battalions, and logistics units.
The Territorial Army was not intended to serve on the frontline. However, territorial units in the northern and eastern regions were engaged in battle to defend their towns and villages.
Thirteen territorial infantry divisions were formed to guard the Spanish and Italian borders, provide coastal defence against a German naval landing, and provide a reserve around Paris. As these threats receded, these divisions were gradually moved towards the frontline.
On August 1st, 1918, all existing territorial regiments were disbanded and their men distributed among the active and reserve regiments. Starting in January 1919, the Territorial Army began demobilising.[4]