NB: This post refers to “Division” as the word is used in land warfare. It may have very different meanings in other contexts. See Wiki:
“While the focus of this article is on army divisions, in naval usage division has a completely different meaning, referring to either an administrative/functional sub-unit of a department (e.g., fire control division of the weapons department) aboard naval and coast guard ships, shore commands, and in naval aviation units (including navy, marine corps, and coast guard aviation), to a sub-unit of several ships within a flotilla or squadron, or to two or three sections of aircraft operating under a designated division leader. Also some languages, like Russian, Serbo-Croatian and Polish, use a similar word divizion/dywizjon for a battalion-size artillery or cavalry unit.“
“The partitioning of armies into ‘divisions’ came into practice in the two French Coalition Wars (France against counter-revolutionary Austria, Russia and Prussia) in the 1790s and the subsequent Napoleonic era, in which armies had to be split up to defend against or attack more than one enemy at a given time or to fulfill tactical assignments, such as outflanking or enveloping manoeuvres.
The definition of a ‘division’ is that it is the smallest sub-unit of an army that can fulfill independent assignments, i.e., the smallest unit that has everything to fight its own small war. Thus said, it follows that a division must have more than soldiers, guns and ammunition: it must have a staff, engineers, signal troops, supply troops, a medical corps, a hospital, kitchen, laundry, map bureau and so forth.
In the First World War, a fully equipped German infantry division would contain the following troops:
4 Infantry Regiments of 3,000 men each; each Regiment composed of 3 Battalions of 1,000 men; each Battalion composed of 4 Companies of 250 men; altogether 12,000 infantrymen;
1 Artillery Regiment consisting of 12 Field Batteries of 6 135 mm guns each and 2 Heavy Batteries of 4 155 mm guns (some divisions had an additional Heavy Howitzer Battalion with 16 150 mm howitzers);
2 Brigades of Cavalry, 680 sabers each, sometimes supported by 2 Field Gun Batteries of their own and a 6 Machine-Gun Company;
1 Squadron of reconnaissance aircraft, 6 machines, pilots, mechanics;
1 Special Artillery Brigade for the discretionary use of the division commander, (54 light 77 mm guns and 18 135 mm guns);
1 Special Machine Gun Company with 6 guns, and
1 Special Artillery Battalion with 18 105 mm howitzers.
Divisional troops, staff and support:
1 Battalion Combat Engineers (Sappers, in German called ‘Pioniere’ (Pioneers);
1 Signal and Communications Detachment with 2 Companies;
1 Quartermaster Train with 2 Companies;
1 Administrative Company;
2 Kitchen Companies (Butchers, Bakers, Cooks);
1 Mail Platoon and Field Post Office;
1 Medical Corps, consisting of 2 Hospital Companies and 4 Transport and Supplies Companies;
1 Veterinary Company;
1 Divisional Staff Company with 4 Detachments: Commanding Officer, Operations Officer (Ia), Supply Officer (Ib) and Intelligence Officer (lc);
1 Map Room;
1 Music Corps, and
1 Company Field Police (MP).
A complete infantry division employed therefore approximately 20,000 men, 7,000 horses and a train of 1,200 supply wagons. Yet a division that had all these troops present and correct would have to be called lucky indeed – for after the first battle most divisions had to do with half of these numbers – or less. In practice – after the huge losses of the first weeks – general staffs often commissioned whole corps take over the independent tactical roles that divisions had been assigned to before the melee had begun.
In terms of vertical composition, two divisions formed a corps, and two corps an army. In practice, as the war dragged on and many units had to make do with smaller numbers, corps tended to get larger, sometimes as big as four divisions. Attrition had halved divisions strengths. When whole divisions were not available or had to be broken up, infantry brigades were used, half of a division – two infantry regiments plus whatever artillery was available.
Every country deviated from the scheme in characteristic ways. French divisions were equipped with a brigade of pre-established reserves, and while their field artillery, the 75 mm gun, was excellent and outperformed the German 77 mm model, they were usually weaker in the larger artillery calibres. British divisions were of somewhat larger size and compensated for an initial dearth of machine-guns with excellent marksmanship. Russian divisions – at least in the early campaigns – were huge, on account of their having not only three but four infantry regiments per division, i.e. sixteen battalions as opposed to twelve. American divisions were truly monstrous, roughly twice as big as German divisions.”
(© John Vincent Palatine 2015/18)