USMC Marine Defense Battalions early in Pacific War

The transition of the Marines from a small specialized naval component to a large scale operational level offensive force has been a recent development in US history. In the 1920s War Plan Orange & the other color plans did not specify the Marines as a major component of amphibious operations. For the ground force in amphibious operations the US Army was to provide one or more corps. The USN did form two Marine Expeditionary Brigades during the 1920s, but those were thought of as small quick reaction forces & not as the primary offensive force for a Pacific war.

The creation of the Base Defense Battalions went far back to before 1914. National politics made it difficult to use the US Army for interventions overseas & the requirement to preempt the Europeans in occupying bankrupt Carribean or Central American nations meant the USN got the job. Thus larger, battalion size, USMC units were experimented with for occupying foreign ports and defending them against other nations looking for their money. The base defense battalions grew out of those experiments.


A Marine Defense Battalion was only a battalion in name. It was actually a Regiment sized combat team in its own right. The Defense Battalion was made up of three “Groups” and a headquarters and support company. The three Groups were:
1. Air Defense Group that consisted of headquarters, three AAA batteries (each having 4 tubes, either 3 in or 90mm) and a searchlight battery.

2. Coast Defense Group that also had a headquarters and three firing batteries (each battery had 2 tubes, weapons were either 5 inch, 7 inch or 155mm guns)

3. The final was a Machine Gun Group that had a headquarters, two machine gun companies, and two AA machine gun companies. The machine gun companies were equipped with 24 .30 cal M1917A1 water-cooled guns, while the AA machine gun companies were equipped with 24 .50 cal M2 water-cooled guns. The Machine Gun Group was used for light AA defense and beach defense.

4. Some of the battalions were also provided with a Tank Platoon of five to eight M2A4 or M3 light tanks.

The Marine Corps did realize that the Defense Battalion was short on rifles. They were putting in plans to add an “Infantry Group” to the Defense Battalion, but the attack on Pearl Harbor put a premature hold on that. Marines were needed to fill out the Marine Regiments that were needed for the Brigades and Divisions. (Rottman, US Marine Coprs 1941-45, 1995) The Infantry Group would have been a D-series Infantry Battalion that would have consisted of a Headquarters Company, three rifle companies and weapons company. But due to the lack of sufficient numbers of Infantry, in the Corps, most of the Defense Battalions only received a provisional rifle company, which was not sufficient for the job it was expected to do. (Rottman, US Marine Corps Pacific Theator of Operations 1941-43, 2004)

As the Marines took the offensive, the Defense Battalions evolved into an almost pure AAA unit. Its Machine Gun Group was transformed into a Special Weapons Group. The Special Weapons Group equipped with two batteries of 20mm AA guns and two batteries of 40mm AA guns. The 20mm guns replaced the .50 cal machine guns.

By 1944, the Seacoast Group was dropped from the Defense Battalion, and it was finally made an AA Battalion. (Rottman, US Marine Corps Pacific Theater of Operations 1941-43, 2004)

it was a detachment from the 1st Marine Defense Battalion that stood the Japanese off at Wake Island. The Battalion was spread in various strongholds on the Island and its features. These strongpoints were set up to cause as much damage as they could to the Japanese landings. There were only 80 infantrymen in the mobile reserve. The Marines held out for 16 days. (Moran, 2011)

It has been suggested that the “Infantry Group” on paper would have made a difference on Wake. The extra companies of infantry would have slowed the Japanese landing forces down, but on the other side of the coin that same Infantry Group would have also been a hindrance on the supplies the island had. Without reinforcement and resupply that advantage of the firepower of the infantry would have been countered by the fact that supplies would have dwindled faster. In the end, the Japs would have still taken Wake, but it would have cost them more and they would have been slowed down only a few days longer.

Here's a few questions for folks who know a lot more about the subject than an old Blue Jacket.
1. Was the Defense Battalion a good idea or were they a drain on already short manpower?

2. Do you think the proposed Infantry Group would have helped them in general, not just on Wake?

3. Did these Marine Defense Battalions provide significant value at Wake, Midway and Guadalcanal?

Moran, J. (2011). Wake Island 1941: A Battle to make the Gods Weep (Vol. Campaign #144). Oxford: Osprey Publishing Co.

Rottman, G. (1995). US Marine Corps 1941-45 (Vol. Elite #59). Oxford: Osprey Publishing Co.

Rottman, G. (2004). US Marine Corps Pacific Theater

 

There was a need for some sort of base defense organization. The battalion at Wake basically accomplished its role, fended off the initial Japanese assault and bought time for a relief effort; you can't expect every little island base to be capable of holding out indefinitely. The battalion at Midway contributed to the heavy losses of Japanese attack planes and would have continued to do so had air attacks continued.

These actions highlight that the main role of the defense battalion was repelling naval and air attack, which makes an integral infantry component seem less necessary. Base defense forces in a long war are going to spend a lot of their time idle, and there's no point in tying down more manpower than necessary. They can always be reinforced by infanty if there appears to be a need, like when a couple of Raider companies were deployed to Midway. Or, like the 3rd Defense Battalion on Guadalcanal, they might have plenty of infantry around already!

This brings to mind one minor thought I had the last time the defense battalions came up - how about making all the machine guns .50s? (until they get replaced by 20/40mm) As I see it, they are mainly for AA, also effective against landing craft - and not bad against personnel but more to the point they could be augmented by .30s and small arms of attached infantry when ground combat appears likely.

This leaves the question of whether defense units should be Marines, Army, or Navy personnel like the Seabees. For example the Army was primarily responsible for both coast artillery and air defense.

 

Very well written presentation. I hope my answer does the question justice.

The Defense Battalions filled one of the cardinal roles of the Marine Corps : "Protect American interests abroad" These were the forerunners of today's Marine Expeditionary Units (MEU). If anything they afforded a more economical use of resources. Adding more bodies to the equation would have taxed the logistical stream on the supply end and having infantry sitting around in the defense, waiting for an attack, would have been a drain as well. Look at Iceland.

No. The more bodies would require more logistical support. The main drawback to larger numbers would mean a bigger drain on fresh waater, a commodity that was in short supply in 1941, while it may not have been as big of a burden on Midway (due to Naval and Air Corps presence), it would have certainly come into play on Wake. Wake a built in source of replacements; 900 civilian laborers which were in the process of building the air strips and infrastrucure.

Short answer is yes. At Wake the Defense Battalion punished the Japanese and set the tone for future engagments, the same can be said for Midway and Guadalcanal.

 

This topic stimulated another thought - a defense battalion was deployed to Midway, and the plan of the islands' defenses in Shattered Sword shows its six 5" guns. There were also four 7" guns and four 3" "anti-boat guns" which do not appear to be part of the battalion's TO&E and were probably installed earlier, which raises the obvious question, who manned them?

There were also twenty 3" AA guns, i.e. more than the defense battalion's usual twelve; perhaps some of them were there earlier, raising the same question.

The 7" guns had been secondary armament on pre-dreadnought battleships and started being removed during WWI when their embrasures in the ships' hulls proved impractical in heavy seas. The battalions' 5"/51 caliber weapons were installed in dreadnoughts statring with the Florida class; again hull-mounted guns took too much water and were either removed or relocated to the superstructure. The Pennsylvania class had as many as 22 originally but were cut back to 12. IMO the 5"/51 was the best secondary gun of its time, except perhaps the Russian 130mm/55.

 

Carronade,

Regarding the 3-inch AA guns...Your forgetting that there were TWO 3-inch antiaircraft groups at Midway - The 6th Defense Battalion's and the 3rd Defense Battalion's - So having only 20 3-inch AA guns would actually leave Midway 4 short.

For whatever reasons, the two AA battalions were intermingled as such:
Sand Island
HQ, Antiaircraft Group, 6th Defense Battalion
Battery D, Antiaircraft Group, 3rd Defense Battalion
Battery D & Battery F, Antiaircraft Group, 6th Defense Battalion

Eastern Island
HQ, Antiaircraft Group, 3rd Defense Battalion
Battery E, Antiaircraft Group, 6th Defense Battalion
Battery E & Battery F, Antiaircraft Group, 3rd Defense Battalion



With regards to the 7-inch & 3-inch Navy Batteries they were manned by the 6th Defense Battalion's Seacoast Artillery Group. Eastern Island's 7-inch and 3-inch Navy Batteries were manned by 6th's Seacoast Artillery Group's Battery A. Sand Island's 7-inch Navy Battery was manned by the 6th's Seacoast Artillery Group's Battery B. Sand Island's 3-inch Navy Battery was manned by the 6th's Seacoast Artillery Group's Battery C.
*Please note that the use of the term "Navy" battery here refers to the coastal batteries and not the 3-inch AA guns.

Here are the commanders of the artillery units at Midway '42:

Seacoast Artillery Group
Commanding Officer
Lt. Col. Lewis A. Hohn
Commanding Officer, Battery A [2 x 5-inch/51cal]
Maj. Loren S. Fraser
Commanding Officer, Battery B [2 x 5-inch/51cal]
Capt. Rodney M. Handley
Commanding Officer, Battery C [2 x 5-inch/51cal]
Capt. Donal N. Otis
Commanding Officer, Sand Island 7-inch Battery [2 x 7-inch/45cal]
Capt. Ralph A. Collins, Jr.
Commanding Officer, Eastern Island 7-inch Battery [2 x 7-inch/45cal]
Capt. Harold R. Warner, Jr.
Commanding Officer, Sand Island 3-inch Navy Battery [2 x 3-inch/50cal naval DP (antiboat)]
Capt. Jay H. Augustin
Commanding Officer, Eastern Island 3-inch Navy Battery [2 x 3-inch/50cal naval DP (antiboat)]
Capt. William R. Dorr, Jr.

3-Inch Antiaircraft Group [i.e., organic to 6th Defense Battalion]
Commanding Officer
Maj. Charles T. Tingle
Commanding Officer, Battery D [4 x M3 3-inch/50cal AA/DP]
Capt. Jean H. Buckner
Commanding Officer, Battery E [4 x M3 3-inch/50cal AA/DP]
Maj. Hoyt McMilan
Commanding Officer, Battery F [4 x M3 3-inch/50cal AA/DP]
Capt. David W. Silvey

3-Inch Antiaircraft Group, 3d Defense Battalion

Commanding Officer
Maj. Chandler W. Johnson
Commanding Officer, Battery D [4 x M3 3-inch/50cal AA/DP]
Maj. William S. McCormick
Commanding Officer, Battery E [4 x M3 3-inch/50 cal AA/DP]
Maj. James S. O'Halloran
Commanding Officer, Battery F [4 x M3 3-inch/50 cal AA/DP]
First Lt. Arnold D. Swartz

From
Pacific War 1941-1945: clarification/correction of Midway's 3-inch guns

 

They could have been organic to the Naval or Air Corps units stationed there or they could have been manned by a Mar Det separate from the Defense Battalion or the Defense Battalion could have been reinforced to accomodate the extra guns or they could have been manned by Army Coast Artillery. The moral of my answer is that these guns could have been manned by any of the above units at any given time depending on when they were manned.

Here is a pretty cool link :
HyprWar: "Condition Red: Marine Defense Battalions in World War II"

 

Thanks, Takao, hadn't known there were two battalions involved. Shattered Sword is actually a bit off on this, guess it wasn't their primary focus. They only mention the 6th but credit it with 24 3" AA, 48 .50-caliber, and 36 .30s, clearly the TO&E of two battalions. Their plan of the defenses shows only five four-gun AA batteries, two on Sand Island and three on Eastern; apparently whoever did their graphics overlooked one.

The intermingling of AA units might be explained by the two battalions arriving at different times. Perhaps the 6th arrived first and divided its batteries between both islands. Then when the 3rd was deployed they might have evened out the AA defenses. I suppose the 5" seacoast guns also arrived with the 3rd?*

* Apparently it's a bit more complicated than that. formerjughead's link and this one
http://www.ibiblio.org/hyperwar/USMC/USMC-M-Midway.html
provide more information. At various times units of the 1st, 3rd, and 4th defense batallions were involved in preparing Midway's defenses.

 

Going from memory but I think it was the 6th and elements of the the other (possibly even pieces of a third).
REsearching it a bit here's a link of interest and a couple of quotes:
HyprWar: "Condition Red: Marine Defense Battalions in World War II"

and

Here's another source for that document:
Condition Red: Marine Defense Battalions in World War II (Battalion Summaries)
Found a reference to some other Marines at Midway:
Midway Islands' Undaunted Defenders – May '96: World War II Feature

I'm not sure what unit the tanks were part of.

Looks like http://www.au.af.mil/au/awc/awcgate/usmchist/midway.txt answers that with a detailed org on Appendix VII

On the otherhand this page http://www.history.navy.mil/faqs/faq81-10.htm states:

 

Can anyone tell me about the 2nd AAA Battalion? I'm particularly interested in Okinawa. How many casualties did it suffer? I'm reading a book that implies it was in the front line as infantry but I'm pretty dubious....