I've been looking for awhile and cantyfi find any information as the name suggests. What I'm after is something that tells me what the average rifle division or regular division of a major belligerent was in strength. Man power battalions, etc. If anyone has any good, reputable sources of information on this sort of thing, I'd appreciate being pointed in the right direction.
For the US, see the terrifyingly named /u/the_howling_cow's answere here. TL;DR - Around 14200 men for a normal infantry division.
For the British the structure on a divisional level was similar to the US structure with "triangular" division consisting of 3 rifle regiments of 3 battalions each. These would typically field somewhere around 13,5 to 18k men depending on when in the war you look. The division generally increased in size as more subunits were added or expanded.
The Soviet Union structure is a little different but an average infantry division would have about 9,5k men in it with Guards Rifle Divisions at around 10,5k. However, there were also NKVD Divisions, Korps and so on. I'm not 100% sure a Red Army infantry division is the best comparable unit to an allied infantry division.
The Germans had several different kinds of infantry division, the larger were almost 18000 men and heavily supported, the smaller were about 15000 men. By 1944 German divisions had "shrunk" by reducing the number of battalions per regiment from 3 to 2 in most divisions (for a total of around 12k men) although some heavier divisions still remaind with a 3x3 structure (around 15k men).
The Italians used binary division from the start of the war, these had as the name implies, two regiments of three battalions each. These typically tabled around 13,5k men.
I don't own any one source for all this information, generally I think you'll have the most luck with finding good numbers in specialized works for each specific army. Like:
The Italian Army 1940–45 - Philip Jowett
British Army 1939–45 - Braylay & Chappell
The Wehrmacht: 1935–1945 - Michael Haskew (German divisions are a fucking mess with a billion complications and different designations for different kinds of infantry units and, towards the end, even little cohesion among division of the same designation)
The US army - pester /u/the_howling_cow until he relents. He knows more about the US army in WW2 than what is normally considered healthy.
Red Army - I don't really have a good comprehensive source for it. I've always struggled to make sense of the Red Army structure. Perhaps /u/commiespaceinvader can provide some help here?