Research - Analysis of which Australian and US battalions were fighting where (Dec 1941 - Dec 1943)

[Aussiegoat]

Hi all,

I'm doing an analysis of Australian and US units in the Pacific to see if I can determine who was shouldering what combat 'load' at at any given time between December 1941 - December 1943. I have completed a spreadsheet listing which units were in action for each month (Dec 1941 - Dec 1943) for both countries, as well as for the entire war for Australian forces.

Some of my initial findings include:
- American battalions were in action for a total of 307 months (cumulatively) vs 267 months for Australian battalions. This is particularly interesting as I've read several times that Australian forces carried the burden of fighting in the Pacific for the first two years. Instead it looks like both countries contributions were relatively similar.
- American battalions were in action for an average of 2.5 months; Australian battalions were for 3.6 months.
- 123 American battalions saw action, compared with 75 Australian.
- There were more American than Australian battalions in action on any given month, for 13 out of 24 months.

I don't want to share what I've done with the wider community until it's finalised (I still want to compare casualty figures and expand US forces to the end of the war, among other things), but I'd love to collaborate with someone who is very knowledgeable about US units during this period, who might like to review my findings and provide suggestions on how it could be improved. Please let me know if you are interested.

Cheers

[rcocean]

- American battalions were in action for a total of 307 months (cumulatively) vs 267 months for Australian battalions. This is particularly interesting as I've read several times that Australian forces carried the burden of fighting in the Pacific for the first two years. Instead it looks like both countries contributions were relatively similar.
- American battalions were in action for an average of 2.5 months; Australian battalions were for 3.6 months.
- 123 American battalions saw action, compared with 75 Australian.
- There were more American than Australian battalions in action on any given month, for 13 out of 24 months. [/b]

Hello AG,

Looks interesting. But what are defining as "Combat"? Did 123 American battalions see "Combat" in the pacific during the time frame? Are you counting the Filipino Army? And what is a "Month"? For example Tarawa was, IRC, 3 days. Is that rounded up to One month or just 10% of a month?

Thanks.

[Aussiegoat]

Hey RC,

Thanks for engaging and for your questions. There are obviously a lot of caveats to my methods, but I've tried to take as practical an approach as possible to solve some of these issues.

- My definition of combat is a battalion that saw 'significant' action during any given calendar month. I've defined significant as: involving the majority of the battalion's infantry/armour/combat engineers etc and a substantial number of the enemy. A battalion held in reserve, even if it was close to the front, that didn't see action was excluded. Likewise a battalion on the front line that was only engaged by small probing enemy patrols or occasional artillery was also excluded (an example of this might be several of the American beachheads in New Britain or New Guinea who's units were happy to stay within their defensive perimeters). I know this definition is open to error with and I'm sure I made mistakes along the way, but I've tried to be as consistent as possible.

And to answer your related question - Yes, 123 different American battalions saw 'combat' between December 1941 and December 1943. I have only mapped those months where battalions saw combat - there were very likely other battalions in these same areas that didn't see 'combat'. In retrospect, I should have colour coded for 'combat' and 'in theatre' or 'reserve' or something similar. I may go back and do this.

- I haven't taken into account the intensity of combat. Some units were in combat for months but the intensity was relatively low; while others were in combat for only a few days but the fighting was intense (such as your example in Tarawa). I plan on including casualty figures as a rough metric of combat intensity, which should another layer on complexity.

- I have not counted Filipino battalions as US, nor Papuan or New Guinean battalions as Australian. This gets a little murky with the 'Philippine Division' (12 Infantry Division) which was part of the US Army, but had only one regiment (the 31st) of which were Americans (although American officers were spread throughout the other regiments). In this case, I counted only the 31st Regiment. This could have gone either way, but I had to draw the line somewhere. Eventually I would like to add Filipino, Indian, English, NZ, Papuan, New Guinean, Dutch and Canadian units to get a more holistic picture, but this is for another day.

I recognise that my analysis is never going to be perfect unless I drill down to day by day, rather than month by month; but considering the already significant size of my spreadsheet and obvious time limitations, this is never going to be possible. So I guess any analysis needs to be taken with a grain of salt. Nevertheless, I think my spreadsheet provides a great snapshot of who was fighting where in any give month, as well as an indication of the different contributions made by the Allied nations.

[Sid Guttridge]

Hi Guys,

An interesting exercise.

The character of the actions of the two armies was also necessarily rather different.

The Australians had a land front in New Guinea that lasted for several years, though not always highly active. By contrast, the US was largely engaged in shorter, island-hopping campaigns with extended pauses between them.

A measure of the intensity, if not the difficulty of the campaigns, might be the casualties suffered by the two armies. Would this not help establish the relative burdens borne?

Finally, there is the issue of who was occupying the active attentions of most Japanese forces?

Cheers,

Sid

[OpanaPointer]

Waves to Aussiegoat.

[Stiltzkin]

Finally, there is the issue of who was occupying the active attentions of most Japanese forces?

China.
http://ajrp.awm.gov.au/ajrp/AJRP2.nsf/5 ... enDocument
Well, its actually the US by casualties with 659,650 deaths versus 199,511 deaths in the Australian combat zone.

[rcocean]

Hey RC,

Thanks for engaging and for your questions. There are obviously a lot of caveats to my methods, but I've tried to take as practical an approach as possible to solve some of these issues.

- My definition of combat is a battalion that saw 'significant' action during any given calendar month. I've defined significant as: involving the majority of the battalion's infantry/armour/combat engineers etc and a substantial number of the enemy. A battalion held in reserve, even if it was close to the front, that didn't see action was excluded. Likewise a battalion on the front line that was only engaged by small probing enemy patrols or occasional artillery was also excluded (an example of this might be several of the American beachheads in New Britain or New Guinea who's units were happy to stay within their defensive perimeters). I know this definition is open to error with and I'm sure I made mistakes along the way, but I've tried to be as consistent as possible.

Thanks for the response. Did you include only infantry Battalions - or include Armor and combat Engineers? IOW, what is a "battalion"? Sorry, for being "nit picky" but I''m trying to understand the parameters of what you're trying to do.

RC

[Aussiegoat]

Waves to Aussiegoat.

Hello again!

Have you flagged this thread with any of the 'wizards' you spoke of? Would be great to get their input.

[Aussiegoat]

Hi Guys,

An interesting exercise.

The character of the actions of the two armies was also necessarily rather different.

The Australians had a land front in New Guinea that lasted for several years, though not always highly active. By contrast, the US was largely engaged in shorter, island-hopping campaigns with extended pauses between them.

A measure of the intensity, if not the difficulty of the campaigns, might be the casualties suffered by the two armies. Would this not help establish the relative burdens borne?

Finally, there is the issue of who was occupying the active attentions of most Japanese forces?

Cheers,

Sid

Hi Sid,

I hadn't thought of who was occupying relative Japanese 'attention'. I'll have to explore that!

Casualties are definitely a useful measure of combat intensity (and I will analyse these soon, but I feel a little uncomfortable equating them to 'burden borne' as I am defining it. By burden, I mean the proportion of fighting, rather than the consequences (deaths) of fighting.

Finally, there is the issue of who was occupying the active attentions of most Japanese forces?

China.
http://ajrp.awm.gov.au/ajrp/AJRP2.nsf/5 ... enDocument
Well, its actually the US by casualties with 659,650 deaths versus 199,511 deaths in the Australian combat zone.

Hi Stiltzkin,

China was not considered part of the Pacific Theatre, but rather the China-Burma-India Theatre. But you're right in that they definitely tied up the majority of the Japanese Army, especially when you take into account the The Kwantung Army (although the Russian threat was definitely responsible too).

How did you come to a total of 659,650 Japanese casualties caused by the US vs 199,511 caused by Australian forces? The figures on the website are interesting but they don't divide 'responsibility' for areas where both Australian and US (and others) both fought - New Guinea and Solomon Islands etc. I plan on mapping out casualties campaign by campaign, which should be relatively accurate; the complication being battles such as Buna, Gona and Sanananda where US and Australian forces were fighting side by side. This is in comparison to Bougainville, for example, where they both fought.

[Aussiegoat]

Hey RC,

Thanks for engaging and for your questions. There are obviously a lot of caveats to my methods, but I've tried to take as practical an approach as possible to solve some of these issues.

- My definition of combat is a battalion that saw 'significant' action during any given calendar month. I've defined significant as: involving the majority of the battalion's infantry/armour/combat engineers etc and a substantial number of the enemy. A battalion held in reserve, even if it was close to the front, that didn't see action was excluded. Likewise a battalion on the front line that was only engaged by small probing enemy patrols or occasional artillery was also excluded (an example of this might be several of the American beachheads in New Britain or New Guinea who's units were happy to stay within their defensive perimeters). I know this definition is open to error with and I'm sure I made mistakes along the way, but I've tried to be as consistent as possible.

Thanks for the response. Did you include only infantry Battalions - or include Armor and combat Engineers? IOW, what is a "battalion"? Sorry, for being "nit picky" but I''m trying to understand the parameters of what you're trying to do.

RC

I included infantry, airborne, armour (NB. Australian units are regiments not battalions) and Australian Pioneer (who served a dual infantry/engineer role) battalions. I haven't yet included American combat engineer units because I wanted to speak with someone who is knowledgeable in this area first. My understanding is that the Australian Pioneers played a much larger combat role between 1941-43 than equivalent US units but I am very willing to be schooled on that!

[Stiltzkin]

How did you come to a total of 659,650 Japanese casualties caused by the US vs 199,511 caused by Australian forces? The figures on the website are interesting but they don't divide 'responsibility' for areas where both Australian and US (and others) both fought - New Guinea and Solomon Islands etc. I plan on mapping out casualties campaign by campaign, which should be relatively accurate; the complication being battles such as Buna, Gona and Sanananda where US and Australian forces were fighting side by side. This is in comparison to Bougainville, for example, where they both fought.

Someone patched up the losses in each sector and posted it on the IJA wiki page. I assume this is a very rough and inaccurate estimate at best anyway.

[rcocean]

My understanding is that the Australian Pioneers played a much larger combat role between 1941-43 than equivalent US units but I am very willing to be schooled on that!

I'm completely ignorant of the Australian Pioneers. I know US Combat Engineers were expected to clear mines, build fortifications and bridges under fire, lay down barbed wire, plant mines, etc. In a pinch, on the defensive, they were used as infantry, sometimes with disastrous results Cf: Kasserine Pass. I'm sure the Marine Combat Engineers on Guadalcanal saw quite a bit of combat. What the Marine "Pioneer" battalions did I'm not sure. Just for curiosity and its easy to find, I looked up Iwo Jima Marine casualties and found:

3rd Eng battalion - 101 losses
3rd Pioneer Battalion - 11 losses

4th Eng battalion - 304 losses
4th Pioneer Battalion - 174 losses

5th Eng battalion -250 losses
5th Pioneer Battalion - 204 losses

Maybe Iwo Jima was unrepresentative. But it certainly would simplify your analysis to exclude American Army/Marine Combat Engineers. I don't think it would effect the overall conclusion.