Roughly how many levels of command were there in a large WW2 army?

Question

I want to build the command structure for a WW2 technology level fictional army. I’m struggling with all of the different units and especially the HQ’s. I need to understand how a real army of this period would have worked so that I can create a believable fictional structure.

I know there is huge variation between nations, periods and branches of an army in terms of organization and naming, but I’m trying establish how many layers of command there might be. Here is a rough scale of increasing organizational size:

Soldier > section > platoon > company > battalion > regiment > brigade > division > corps > army > army group > Supreme command

Which of these units would expect to have officers looking at maps and directing lower level units? And which units are effectively just containers for the units below them, exist only for logistical or administrative purposes or are just different names for the same thing in a different branch so don’t count?

This assumes a very large scale operation such as The D-day landings, operation Barbarossa, operation Uranus or similar to get the full scope of command levels.

Answer 1

Most of these levels will have officers receiving orders from above, interpreting them, and issuing orders to lower echelons. But these events won't all happen at the same time.

To take the D-Day landings as an example, the supreme commander (Eisenhower) and the initial Army Group commander (Montgomery) will have made their main plans, in consultation with each other and their respective staffs, months in advance. The Army commanders, Bradley and Dempsey, will have made their plans on that basis, still well in advance, and issued orders to their corps commanders. There was one corps per beach, so each corps commander is fairly independent of the others.

For a beach, the corps commander will have allocated his divisions in consultation with his staff and the divisional commanders and staffs. That gets us to the divisional level.

Then we hit a difference in terminology and organisation. The Commonwealth divisions were made up of brigades, each of which contained several battalions. The American divisions were made up of regiments, each of which contains several battalions.

A British-tradition regiment is an organisation that creates and trains battalions, which are then assigned to brigades, but almost always to different brigades. It isn't a combat unit as such, but a centre for training and traditions. A US regiment is a combat unit, and has the same set of battalions, almost all the time.

In any case, the divisional commanders would give objectives to the commanders of their brigades and regiments, and those commanders would allocate the objectives to battalions, probably holding a battalion in reserve. We're still a couple of months in advance of the invasion here.

The battalions are the tactical units. Their commanders would do the detailed planning for the attacks in their areas, and would hold map exercises to test their plans. The troops, meanwhile, would be practicing disembarking from landing craft, and rehearsing their attacks on dummy versions of the targets. These exercises will inevitably find problems with the plans, which will have to be adjusted.

On the day, the company, platoon and squad levels of command are on the ground with their men. Their jobs are to take their targets, finding other ways to do the job if the defenders resist, helping out neighbouring units if they can, and calling for support if they need it. The battalion HQs may be on the beach or on ships, and their job is to decide where to commit their reserves, and to tell higher HQs if they are having problems.

Brigade/regiment, division and corps HQs are on board ships. They might have two levels on the same ship, but they definitely won't have all three, because that means too much is lost if a ship is disabled or sunk. Their job is to feed their own reserves to lower levels, and tell higher levels what's going on. Army, army group and supreme command are in England. They need to stay out of the lower levels' hair and let them get on with the fighting.

Once Eisenhower had given the "go" order, he didn't need to give any more unless there was a disaster: everything had been pre-planned and everyone knew what to do. The orders that it would have been meaningful for him to give would have been endorsing the army group's decision to abandon a beach that could not be taken, and abandoning the whole attack, which is the supreme commander's decision. Giving orders to commit a reserve battalion or company is not his job - he doesn't have as good information as the commanders closer to the action, and he needs to keep track of the overall situation.

Supreme command involves a lot of responsibility without the ability to do very much to help on the day.

Answer 2

John's answer is a good start, but the D-Day landings were unusual. Planning and preparations for D-Day and H-Hour was extensive, with non-typical secrecy requirements to maintain surprise. So here comes my take on your question:

American doctrine talks about organic subunits and attached or assigned or supporting subunits. These are terms with clearly defined meaning, but roughly an organic subunit would be part of the unit unless specifically detached for a special situation while attached subunits are not normally part of the unit, and only come for specific purposes.

In combat, units operate as combined arms teams. It is almost never a pure tank unit, or a pure rifle unit, or a pure artillery unit fighting a battle. Some of this combination can be organic, like an infantry battalion having rifle companies and a mortar company, but an infantry battalion would not have the right mechanics and ammo and fuel trucks to keep a tank company running. So if the infantry battalion needs a tank company, that would usually be attached. Same if it needs an artillery battalion, or a pontoon bridge company.

A headquarters that is expected to detach all subunits during combat operations is a purely administrative headquarters. That would be the British-style Regiments John mentioned, but also pools of special resources with a common superior for ease of training, supply, and so on.

So to get back to WWII in particular:

• There usually was an unit of a few dozen men under the command of a very junior officer with the aid of a very senior sergeant, or just a very senior sergeant. That is the platoon. There would usually be sub-units called squad or section under the command of a sergeant, and perhaps sub-units under that led by a corporal. In armor or artillery, a vehicle plus crew replaced the squad.
• There usually was an unit of a hundred or two hundred men under the command of a more experienced officer. That is the company or battery. A company has a headquarters with the commander, probably an executive officer, a very senior sergeant, and few specialists like armorers, mechanics, radio, supply, cooks, but there is no staff.
• There was usually an unit combining several companies. That is called the battalion in American usage. If it is infantry or armor, it would usually fight as a combined arms team, either by attaching a company of the other type from somewhere or by swapping a company. (Three infantry and one armor battalions could make three or four combined arms units, respectively. Making it three means there is a battalion headquarters sitting idle, making it four means none of the units has all of the sub-units present.)
  Battalions usually had the staff to manage things: a logistics officer and not just a supply clerk, an operations officer to write plans, and so on.

Above that level, things could and did differ. A division would have roughly ten battalions worth of infantry, armor, and similar units, and another ten battalions worth of supports like artillery, engineers, and the like, and they would usually but not always get divided into an intermediate level for combat. That could be called brigade, regiment, group, combat command and more names. Those intermediate-sized units could also be directly attached to corps or armies.

Also note that talking about tanks is somewhat biased towards the well-equipped US forces late in the war. Instead there might be assault guns, tank destroyers, anti-tank artillery, or armored cars. An US infantry division might have had one battalion of tanks, one battalion of tank destroyers, and some sort of mechanized cavalry to support their infantry. That means not every infantry battalion could get a whole company of tanks, as I had optimistically outlined above.

Answer 3

Battalion and Above

Which of these units would expect to have officers looking at maps and directing lower level units? And which units are effectively just containers for the units below them, exist only for logistical or administrative purposes or are just different names for the same thing in a different branch so don’t count?

So the other answers have been phenomenal describing the layers of command and answering the overall question. I just wanted to add a bit to directly answer the above.

Firstly I take it by stand around and look at maps you are talking about officers who lead by radio rather than being actually out in the fighting with their troops. An officer who fights on a map away from the actual front line and only sees the enemy in person if they're having a very bad bay. This sort of command begins at the battalion level, with a few exceptions.

At the battalion level in WWII, the various companies were usually too far spread to be commanded "by eye" this also was somewhat of a problem at the company level, especially for infantry companies. However at the company level all combat company commanders (meaning infantry/armor/artillery, support units are largely similar but its less universal) can expect to be with their men, in the line of fire. Now an infantry/artillery commander can and should be somewhat "behind" the line to be able to direct his men rather than fighting himself, but they're all more-or-less in as much danger as any one of their men. Transportation units, however, could have their company commander set up in a given town spending all his time with paperwork while his men drive back and forth between the town, and wherever they're taking supplies to.

• Armor commanders (tanks/tank destroyers/armored cars) are GENERALLY in a tank themselves, and must fight said tank. They also have fewer maneuver units and therefor have a somewhat easier time of managing "larger" formations. (For example, a US Tank Battalion in 1943-45 comprised of 3 companies of 18 tanks divided into 3 platoons of 5 tanks and 3-tank company command, plus maintenance and supply troops that wouldn't (in theory) be involved in active fighting. This means that even a micro-managing battalion commander only has 54 individual combat units to deal with in a fight. Whereas an infantry battalion could have several hundred individual soldiers.) Plus armor battalions could be split up across a wide area supporting other units, so the battalion commander (who has his own tank as good as anything else in the battalion) might have 1st and 2nd company detached to formations X and Y, and take personal command of 3rd company which is detached to formation Z. So you see a decent amount of battalion/regimental armor officers up front and fighting in the same manner as, say, an Infantry Company Commander.
• Once you get to commanders of brigades and above, you are exclusively in "giving orders whilst looking at a map" territory, except for the occasional oddball commander. And even generals like Patton (famous for being further forward than he should have been on occasion) will spend almost all of their wars ordering people into battle rather than being in range of the enemy themselves.
• Air Forces/Corps. Squadron and Wing Commanders (roughly equivalent to battalion/regiment and brigade commanders) would routinely fly missions in most air forces during the war.

In WWII the only thing that might conceivably be a "container" unit is the British "regiment". In Continental & US armies the Regiment was the equivalent of the British Battalion, and various British battalions/US regiment made up brigades etc as already has been pointed out. The British still had "paper" regiments, but they were effectively meaningless in wartime. It goes back to the days of Muskets in the 17th and 18th centuries, where British regiments would have 2 (usually, sometimes more) battalions in a regiment. Eventually it became policy for one battalion to be in England as a recruiting/training battalion while the other battalion went abroad for service. Long story short eventually there was nothing really connecting regiments, and British regiments had become an awkward size for brigades anyway so they ditched the "regiment" as a tactical element. So by WWII the 1/44th and the 2/44th shared a "regimental" name, but were distinct and unattached in any way.