Organization of a Territorial Division

1914

In the summer of 1914, there were 15 territorial divisions (81st-92nd, 94th, 96th-97th and the Belfort Division) which were assigned mostly to the defense of Paris, the Alps and the coasts. The exceptions to this were the 90th and 94th D.T. The former (sent to North Africa and Morocco) was disbanded and reassigned to the 94th D.T. in September. Soon after, the 94th D.T. was disbanded in October, with the various regiments being reassigned to other territorial divisions. All territorial divisions remained unattached to the army corps', though a certain number of divisions could constitute a reserve division group. A territorial division was composed of 2 brigades of 2 regiments. The number of battalions in a territorial regiment varied depending on the size of the local population -- as few as 2 and as many as 7, but most were composed of 3 or 4. Overall, the territorial it was smaller than both the active and reserve division.

Number of Effectives (When at Full Strength)
Division: ~8-12,000
Brigade: ~4-6,000
Regiment: ~2-3,000

August 1914

Division

Administration:

General-Staff

Troops:

2 Brigades of Infantry (2 regiments each)

2 Squandrons of Cavalry

1-2 Groups of Artillery

1-2 Companies of Engineers

1 Telegraph Detachment

Services (varied according to the division):

Quartermaster Formations

Medical Formations

1915

In 1915, following the amalgamation of non-divisioned formations, an additional 6 territorial division are formed: the 99th-101st in February, the 102nd in May, the 103rd-105th in August, the last of which was formed from the Belfort Division. In the same year, however, 5 territorial divisions are disbanded: the 82nd, 84th, 91st-92nd and 96th in June and July. Meanwhile, the regiments of the 85th and 86th D.T. were reassigned to active divisions.

1916

In 1916, coinciding with the dissolution of the infantry brigade and subsequent reorganization of the divisional infantry, 4 territorial divisions are disbanded: the 99th in August, and the 102nd-104th from March to August (save the 104th, disbanded in November). Meanwhile, the 105th D.T. is formed into the 133rd active division. Thus, by the end of the year only 7 territorial divisions were extant.

1917

In 1917, the 7 remaining territorial divisions were disbanded, save one (the 83rd D.T.) which was reserved for the military government of Paris. The 89th (in June), 100th and 101st (in January) were dissolved entirely. Meanwhile, the 81st, 87th-88th, and 97th were transformed into active divisions. However, 2 new territorial divisions would be formed up due to an increased strain on manpower.

1918

In 1918, the 2 territorial divisions created the year before were transformed into dismounted cavalry divisions. Thus, at the end of the war, there is only 1 territorial division still extant.

Sources:
British General Staff, ed. Handbook of the French Army, 1914. Battery Press: Nashville, 2002.
Sheffield, Gary, ed. War on the Western Front: In the Trenches of World War I. Osprey Publishing: Oxford, 2007.
Sumner, Ian and Gerry Embleton. The French Army 1914-1918. Osprey Publishing: Oxford, 1999.
Vauvillier, François. Nos Poilus de 1914-1918: L'Infanterie. Histoire & Collections: Paris, 2006.