To start with, let's say each person in our unit eats 1.6 kg/day of food. That's somewhere between WWII US and Japanese rations in weight, which I think is reasonable for a country not as prosperous as the US but also not believing its soldiers can eat grass if they have a strong enough fighting spirit. I'd like to insist that this
not be forage, at least under peacetime circumstances, because it tends to result in animosity - my grandmother bore a grudge against the Germans her entire life, in no small part due to remembering trying to hide the family's chickens from soldiers during the war. There are also arguments to be had about how taking food from civilians with the threat of violence can result in a fucked up army culture.
As for draught animals (and people), we can start with pack mules; those can carry about 130 kg; in turn, they require 4.5 kg/day of hay or straw to graze on and an additional 2.25 kg/day of barley. Porters can carry about 50 kg and require the same food as any other person. As for horses, small ponies can live off of grass, but larger horses require about half their diet to be special feed; a horse will eat 2% its bodyweight in food each day, and can pull a wagon weighing up to 1.5 times its bodyweight. Using Japanese WWII carts as a basis of cargo/total weight, this results in a horse being able to pull about 350 kg of cargo atop a wagon and eating 4.5 kg/day of foraged hay and 4.5 kg/day of barley or other high quality feed. Oxen can get by with proportionately more grazing (Boran cattle, which are what the Oromo raise, are apparently notable for their tolerance for low quality feed and ability to graze on the trot), but still need a similar 2%. Oxen can also pull about 2.5-3x their bodyweight; this results in a Boran ox being able to pull about 850 kg of cargo atop a wagon and eating 13 kg of foraged grass or hay a day. A truck, obviously, requires no forage, and only around a few gallons of gas per day for several tons of cargo if moving at the sedate pace of walking infantry.
Aside from food, there are other necessary supplies. The US in the Pacific had this as:
3.11 pounds (1.41 kg) of clothing, replacement vehicles, and other general supplies (Class II), 10.67 pounds (4.84 kg) of fuel and lubricants (Class III), 15.46 pounds (7.0 kg) of medical, motor maintenance, quartermaster, construction, and other miscellaneous supplies (Class IV), and 9.58 pounds (4.35 kg) of ammunition (Class V).
The British were much less, at 8 kg per soldier being delivered at the corps level. At the company level, I think we can say most of that isn't going to be actively consumed; instead, I'd just add 1.4 kg to our previous 1.6 kg for 3 kg/day per person, plus ammunition.
As for ammunition, thankfully, there's info on how many rounds of ammunition the Japanese expected a fighting unit to consume over an average four-month period per weapon, with 2/3rds of that time being spent in active combat (
Kaisenbun). Each rifle was expected to need 300 rounds, and each light machine gun, 8000 rounds. For contrast, the US unit of fire (roughly 1 heavy day's fighting) was around 100-150 rounds for a rifle, 1,500-2,000 rounds for a LMG, 3,000 rounds for a MMG, 1 grenade per enlisted man, and 100 60 mm mortar bombs. The ratio of rifle:LMG ammo seems to suggest that the US expects the rifleman to be shooting a fair bit more often than the Japanese do; I'm going to split the difference by giving each rifle 450 rounds. If we divide this by the 80 days of combat that Japanse
Kaisenbun represents, this gives us something like:
- 5.625 rounds/rifle/day
- 100 rounds/LMG/day
- 200 rounds/MMG/day
- 0.025 grenades/rifleman/day
- 2.5 mortar bombs/mortar/day
Per a person on discord who has some 6.5 Carcano clips and a scale (which are presumably not too different from 6.5 Arisaka clips in overall mass), they're negligibly heavy; we're probably looking at about 23 g per round. An ammunition box for rifle rounds seems to add around 15% to the weight. Machine gun strips and the ammo box, meanwhile, seems to add about 80%. I'm going to assume grenades are about 0.6 kg; mortar bombs for the Type 89 were about 1 kg. For a company with 207 rifles, 9 LMGs, and 2 MMGs, this is 33.9 kg of rifle ammo (and grenades) per day, 37.3 kg of LMG ammo per day, and 16.6 kg of MMG ammo per day; overall, this is around 90 kg per day of consumables. Ofc, we're only fighting 2/3ds of the time, so let's say it's 60 kg.
I am NOT going to get into water usage. I am assuming we have water supplies, because if we don't, then it is infeasible to use anything but motor transport and I will leave it at that.
Anyways, add this 60 kg to the 200*3 kg we have from the non-transportpersonnel, and we need 660 kg/day of consumables to keep a company in the field ignoring the logistics burden of the logistics apparatus itself. Assuming a 1:1 ratio of animals to handlers (which seems to roughly be the historical practice, give or take a few), we can then calculate the food requirements for the animals and their handlers, add that to the transport requirements of the rest of the company, and solve for how many we need (i.e., 0=[# of days autonomy]*660 kg/day+[# of animals]*[# of days]*[animal+handler supply consumption in kg/day]-[# of animals]*[carrying capacity of animals in kg]).
The results are presented in the graph below.
I suspect fitting the wagons onto the train to be more of an issue than the animals.
