Marine Unit Designations

There continues to be a great deal of confusion regarding Unit Designations for the Marine Corps. While it makes perfect sense to most Marines and former Marines; it makes absolutely no sense to anyone else, especially if they try to interpet the unit designations with the Army standard.

Price already has a pretty good head start on it and hopefully he will pick up this ball and run with it further.
-Brad

Interesting stuff Steve, but you've confused me a little with your nomenclature. Marines is the designation given to Marine Corps Regiments. When you used it here: "He later served in Korea with the 5th", I assumed you were speaking of 5th Marines, one of the 1st Marine Divisions three component infantry regiments, it was the 1st Marine Division that served in Korea. When you used it here: "He served with the 5th, 27th, Signal Co." It appears it is the same unit but is actually the division not the regiment, 27th Marines were a part of the 5th Marine Division.
When you use it here: "was KIA while serving with the 5th Marines, 26th, on 3/3/1945.... Irvin McKinnon..." You must have been referring to the 5th Marine Division, because 5th Marines were not at Iwo Jima, and the 26th Marines were at Iwo Jima and part of the 5th MarDiv. (26th, 27th and 28th Marines (Infantry Regiments) and 13th Marines Artillery).
Historians screw this up all the time in many books and it really gets confusing. One of the worst is when writing about Saipan and they continually get Second Marines confused with the 2nd Marine Division, one of the 2d MarDivs component regiments (2d, 6th and 8th Marines (Infantry) and 10th Marines (Artillery). For example "The 2nd Marines landed on the left of the 4th Division on Green and Red beaches with 6th Marines as the far left flank." Well 2nd Marines weren't part of the initial landings the author meant the 2d Marine Division or simply Second Division.

 

I confess, I am clueless when it comes to the Marine units. I have tried but I never get them right. I should have just posted their names and info...

 

Not at all my friend, you have all that great history in your family, understanding the way they were designated helps clarify what actually happened when reading an official history or one where they get the designations correct. It really is simple, I for one would be glad to help explain it to you if you're interested.

 

You also illustrated to others (or at least me) some problems I wasn't aware of. I learned something because you posted it that way so thank you. And of course Price as well for pointing it out.

 

That would be great !

I get the Rangers and 1stSSF units, but the designations for the proud USMC confuse me. Thanks for your help in advance.

 

I'll second that request.

 

You're in good company, Steve! This was new to me, too. It does make sense when explained as Price did, but it is understanding that folks (like myself) might be confused.

 

I'll attempt to provide a clear explaination, all questions, comments, clarifications or requests for clarifications will be appreciated. I'll start with the most common error, and one that many history writers make and that is the correct useage of the term "Marines".

“MARINES”
This is the easiest topic. When discussing Marine Corps unit designations, the term “Marines” always refers to a regiment. Never a division or brigade or any other unit type. Regiments can be refered to in other terms, but “Marines” always means the same thing, regiment. If applied to any other unit type it is incorrect. We’ll use the First Marines as an example, it can be expressed as First Marines, 1[SUP]st[/SUP] Marines, 1[SUP]st[/SUP] Marine Regiment, 1[SUP]st[/SUP] Regiment, etc. Because 1st Marines are a component regiment of the 1st Marine Division, I assume that many people not familiar with the proper usage of the term and working from official documents or participant accounts get the two confused. Once you understand that Marines always applies solely to the regiment it makes understanding who did what much clearer. Unfortunately, many authors once they confuse the two, begin referring to the division with the appellation "Marines" and it clouds the understanding of what actually occured in the event being described. I have seen the example, I gave in the previous post, concerning Saipan several times when reading histories that discuss that battle.
"One of the worst is when writing about Saipan and they continually get Second Marines confused with the 2nd Marine Division, one of the 2d MarDivs component regiments (2d, 6th and 8th Marines (Infantry) and 10th Marines (Artillery). For example "The 2nd Marines landed on the left of the 4th Division on Green and Red beaches with 6th Marines as the far left flank." Well 2nd Marines weren't part of the initial landings the author meant the 2d Marine Division or simply Second Division."

The Marine Corps generally employs their infantry units with attached assets in order to make them a more capable formation, (we’ll cover these assets more fully under divisions). What I’d like to cover here while we are discussing regiments is when a formation is referred to as Regimental Combat Team (RCT) or Regimental Landing Team (RLT). An example would be when reading about Tarawa they might refer to RCT-8 (Regimental Combat Team 8), this is just a regiment with the necessary attachments to perform their assigned task, be it artillery, medical, motor transport, assault amphibian, anti-tank, armor, etc. The number almost always corresponds to the regimental number of the ground combat element of the RCT, in this case 8 for 8th Marines. In an RCT or RLT the regimental headquarters controls the ground combat element and attachments, this differs from a brigade where a higher headquarters controls the ground combat element(s), and attachments. Brigades in Marine Corps usage are made up of one or more regimental sized ground combat elements, attachments and a higher (brigade headquarters). The components of the 1st Provisional Marine Brigade in Korea is a good example:

H&S BN 1st Provisional Brigade
-Det. 1st Signal Bn
-Co. A 1st motor Transport Bn
-Co. C 1st medical Bn
-Co. A 1st Shore Party Bn
-Co. A 1st Engineer Bn
-Det. 1st Ordinance Bn
-Co. A 1st Tank Bn
-1st Bn 11th Marines (artillery)
-4.2 Mortar Co. 1st Weapons Bn
-75mm Recoiless Gun Co.
-Det. 1st Service Bn
-Det. 1st Combat Service Group
-Det. 1st Reconaissance Co.
-Det. 1st Military Police Company
-1st Amphibian Tractor Company
-1st Amphibian Truck Company
5th Marines (GCE)
MAG-33
-3 x F4U Corsair Squadrons
-1 x VMO Squadron (observation; light fixed and rotary winged aircraft)

I think the list illustrates how, when deployed a Marine brigade, RCT, RLT, etc. is organized to be a self-contained, combined arms unit with all necessary supporting components. You can think of it as a smaller version of the division itself. When the 1st Marine Division arrived in Korea, the brigade was dissolved and the component parts returned to their parent units. The previous time the 1st Provisional Brigade was stood up was when it served at Guam, during that iteration it contained two infantry regiments as its ground combat element, 4th and 22d Marines, plus attachments to include a provisional artillery battalion. The time before that was when it was sent to Iceland to defend against invasion by the Germans, that time it had the 6th Marines as its ground combat element, various attachments including 2d battalion 10th Marines (artillery), a platoon from 2d Tank Bn, an anti-tank and parachute platoon. Task organized.

The first permanent (so to speak) regiment was 2d Marines, formed on 01 January 1901, due to the situation in the Philippines. The 2d Marine Regiment or 2d Marines, was formed from Marines returning from fighting in the Boxer Rebellion. The reason they started with the 2d Marines instead of 1st Marines, is that there was in existance at the time a 1st Provisional Regiment. Since that time there have only been twenty-nine numbered regiments, plus the 1st Raider and 1st Parachute Regiments. (There was a 2d Raider Regiment (Provisional) for the Bougainville operation, but it too was a temporary, Ad Hoc unit). The 1st through 9th Marines, or 1st through 9th Marine Regiments are infantry regiments. 10th Marines through 15th Marines are artillery regiments (11th Marines were originally raised as an Infantry regiment for service in WWI and was deactivated after the war, when reactivated for WWII they were and remain an artillery regiment). The 16th through 20th Marines were engineer regiments attached to the divisions. The 21st through 29th Marines were again infantry regiments.
To reiterate: 1st through 9th Marines and 21st through 29th Marines are infantry regiments. 10th Marines through 15th Marines are artillery regiments. 16th through 20th Marines were engineer regiments. These latter were deactivated during WWII, I'll tell more about the engineer regiments in another post. I earlier stated, "The first permanent (so to speak) regiment...", the reason for adding "so to speak" was because all Marine regiments except for 5th Marines have been activated and deactivated multiple times since the first "permanent" regiment was created. The regiments have been stood up when required, and deactivated once the emergency had passed, many more times than most people would think because more often than not it was for situations short of full scale war. 5th Marines alone has been in continuous existence since it was first stood up, June 18th, 1917 for service in France.

 

Holy cow, Bob! That's a history lesson in a nutshell. Thank you. I've been trying to wrap my head around Grandpa Solovic's service history for . . . well . . . years. That helps.

Also: Did you guys make the ribbons at the bottom of your posts? I'd love to do one in honor of my grandfather if I can figure out what ribbons he has on his board and so forth. (I know he has a marksmanship medal, a few purple hearts, and a variety of WWII theatre and battle ribbons. There are several other medals there as well, though I know not precisely what. He's explained it and it's never quite sunk in entirely.)

 

Like any language...its far easier if you're emmersed in it and you have to swim or sink...

 

Yeah, I did get a little long winded, . Your eyes may be a little glazed over also sorry.


The term Marines when applied to a Marine Cirps unit means regiment. (The simple version)

 

Battalion Designations and Structure:

In most cases ask a Marine who he served with and he'll usually give you the regimental designation (5th Marines) or give you a series of numbers or a letter and numbers (3/5 or K/3/5). You'll run across the same series of digits when reading histories. This part is really simple and allows a person to brief, but very specific. Ever since the Marine Corps adopted the triangular structure, which they still use, an infantry regiment/"Marines", has three battalions, numbered 1,2,3. Each battalion has three infantry/rifle companies and a weapons company. The designation of the weapons companies has varied over time, they originally had a letter designation and later went to simply weapons company x/x. To designate or when speaking of the battalion within the regiment it is battalion/regiment, so 3/5 would be 3rd Battalion 5th Marines, 1/2 would be 1st Battalion 2d Marines, 2/26 would be 2d Battalion 26th Marines. So if you were to read the Second Marine Division landed on Red beach two with, (L to R) 2/6, 3/6 and 2/2, with 1/6 as regimental reserve, it becomes easy to decipher. They landed on Red beach two with 2d Battalion 6th Marines (Regiment) on the left flank, 3d battalion 6th Marines in the center, and 2d Battalion 2d Marines (another regiment) on the right flank. The 1st Battalion 6th Marines was held in reserve. Since all three battalions of 6th Marines are accounted for and the 2d battalion of another regiment (2d Marines) was included in the landing, either 2d Marines (the regiment) are being held as a subsequent wave or as reserves, or 6th Marines are acting as an RCT, RCT-6 with the attachment of a battalion (2/2) from another regiment.
Head still hurting Lou, wait till I tell you about companies. Eugene Sledge of "With the Old Breed" fame served in K/3/5. In my next post I'll explain about the letter that goes with the numbers.

 

So first company of the first battalion of the fourth marines would be 1/1/4? At a guess? Why can't we just have something simple and sensible like MarDiv 1 of MarRon 4 with CBG (pronounced seabag, of course) presiding? And of course MarRon 4 could be assigned to MF 6 as the primary element, making MarRon 4 functionally synonymous with MF 6.1. That is assuming that you find DesDiv, FitRon, C(x)AG, and TF x.n.y sensible.

If it makes you feel any better Army unit designations are just as mysterious to me. Actually, more so, as your explanation has cleared Marine designations up considerably. You and Gebirgsjaeger have consistently lost me with your ToFs since I can't even follow which units are bigger and which smaller in Army parlance. This land stuff may simply be more organizationally complicated.

 

Maybe I'll get a thumbnail sketch going for Price.

Marine Corps structure is very dynamic making it an incredibly flexible fighting force. The base unit for the Marine Corps division is, and always has been, the individual rifleman. With the goal of the Marine division to place a bayonet in the body of the enemy; this is illustrated in the following Marine mission statements: "The Mission of the Marine Corps (rifleman, fireteam, squad, company, battalion, regiment, division), in the offense, is to: locate, close with and destroy the enemy with fire and manuver." Also the Mission of the (pick any sized Marine unit) in the defense, is to: repel the enemy's assault with fire and close combat."

With that in mind everyone has heard the old saying: "Every Marine is a Rifleman", this is akin to the Army motto : "Every soldier is an Infantryman"; this is where the fracture between Army and Marine unit designations begin: Rifleman v. Infantryman or to be more specific: Rifle v. Infantry.

So, the Marine Corps will refer to "Infantry" companies one of two ways: "rifle" or "line", the terms "rifle" and "line" are synonomous.
Each "line" company in a battalion willl be given a letter designation as follows:
1st Bn.: A, B, C and (sometimes) D
2nd Bn.: E, F, G, and (H)
3rd Bn.: I, K, L and (M)

In addition to the "lettered" line companies, in each battalion, there is also a Headquarters and Service (H & S) and Weapons (Wpns) company
The same lettering format can be used for Artillery units with "battery" being substituted for "company"

Here is a link to one of my favorite websites. IT has a more in depth explanation : http://ww2gyrene.org/

 

Great post and a very good site sir. I had been preparing a post on the lettered companies, but Brad's is succinct and to the point. So, if he has no objections I will build upon it. As Brad wrote 1st Bn has three rifle companies A, B, & C, the early part of WWII Wpns Company had a letter designation also D. The companies continue to be assigned letters sequentially, so 2nd Bn had E, F, G and H as Wpns Co. Then 3rd Bn had I, K, L and M as Wpns Co. (J is not used because when written it can become confused with I). Later in WWII and through Korea the letter designation for Wpns Co. was dropped and it became simply weapons company and the battalion number. The line companies were still numbered sequentially so A, B, C was 1st Bn, D, E, F 2nd Bn and H, I, K Third Bn, the three weapons companies were still there, but simply called Weapons Company and the battalion. Post Korea the present system came into being, I'm not sure of the exact date, but can find it if anyone requests it. It is exactly as Brad laid out (D, H, and M being reserved for a fourth rifle company if required, Wpns Company designations remained unchanged.

So let me use 5th Marines as an example:
WWII early: A/1/5, B/1/5, C/1/5, D/1/5 (the WpnsCo.)---E/2/5, F/2/5, G/2/5, H/1/5 (the Wpns Co)---I/3/5, K/3/5, L/3/5, M/3/5 (the Wpns Co)

Late in WWII with the Series G, TOE the Weapons Companies were eliminated and their assets moved into Battalion HQ Company as the 81mm Mortar platoon and the machine guns moved down into the rifle companies.

Korea: A/1/5, B/1/5, C/1/5, WpnsCo/1/5---D/2/5, E/2/5, F/2/5, WpnsCo 2/5---G/3/5, H/3/5, I/3/5, WpnsCo 3/5.

Post Korea to current: A/1/5, B/1/5, C/1/5 (D reserved) WpnsCo 1/5---E/2/5, F/2/5, G/2/5, (H reserved) Wpns Co 2/5---I/3/5, K/3/5, L/3/5, (M reserved) Wpns Co 3/5.

In some cases you will read the designation expressed as simply the company letter and the regiment, example K/5 or K/5th Marines. This is not a common practice, but will see it frequently enough, this is because the battalion number is actually redundant, as "K" Co will always be in the same battalion regardless of the regiment.

 

So how about a practical application exercise?

From the Wikipedia entry on John Basilone: "The Corps sent him to Guantánamo Bay, Cuba for his next assignment and then to Guadalcanal in the Solomon Islands as a member of Dog Company 1st Battalion, 7th Marine Regiment 1st Marine Division."
Early war, Dog or "D" company was the Weapons Company for 1/7 and Basilone was a heavy machinegunner so he would have been assigned to a Weapons Company.


Excerpt from Korean War Educator site on fighting around Chosin Reservoir: (my comments in blue)
"To How Co's (had to be a third battalion unit because of what we know about company designations) left, the positions of LtCol Hal Roise's 2/5 (2d Bn 5th Marines) were under an equally fierce onslaught. Just a year earlier Roise had been the head coach of the Camp Pendleton, Calif., football team, preparing his gridders to meet Quantico, Va., in the All-Navy championship game before 45,000 spectators in the Los Angeles Coliseum. Now there appeared to be that many Chinese assailing Roise's lines. Rank after rank of them flung themselves against Roise's two forward companies, Easy and Fox (Companies E & F 2/5). They were shot down in windrows, bodies tumbled atop bodies, but still they came on. Inevitably the weight of numbers produced local breakthroughs. They were sealed off and thrown back. It was a goal line stand of a different sort. The battalion held. he situation was no less tense on the hills to the right of Hill 1403 in the sector of 2/7 (2d Bn 7th Marines). The Marines of Capt Walt Phillips Easy Co (E/2/7) on Hill 1282 and Capt Milt Hull's Dog Co (D/2/7, we know this is an infantry company because by Korea, Wpns Companies were no longer letter designated, and if pre-designation change "D" would have been in 1/7) on neighboring Hill 1240 were confronted by their own seas of Chinese attackers as the fighting descended into hand-to-hand savagery. Casualties on both sides were crippling. The slopes of both hills were covered with the human wreckage of repeated Chinese attacks. The ranks of the defenders were no less fearfully depleted. After a night of constant combat, Easy Co (E/2/7) had been reduced to the strength of less than a single platoon, all of its officers except one killed or wounded. Twice wounded but continuing to lead, Milt Hull, who would receive the Navy Cross for his night's work, could muster only 16 Dog Co (D/2/7) Marines still on their feet and able to fight."

From HyperWar, Tarawa:

"The order for landing issued by Col. David Shoup called for the employment of three of the landing teams under his control in the assault and one team in reserve. Attached to the 2d Marines was the 2d Battalion 8th Marines, commanded by Maj. Henry P. Crowe and this reinforced battalion was assigned the mission of landing on Beach R[SIZE=-1]ED[/SIZE] 3, to the left, or east of the long pier which extended from the north side of the island for some 500 yards. On the right of Crowe's battalion was that of Lt. Col. Herbert Amey, the 2d Battalion, 2d Marines. Amey was to land his battalion on Beach R[SIZE=-1]ED[/SIZE] 2, on the right, or west, of the long pier. This beach was about 500 yards wide and its right flank rested on that part of the western portion of the northern side of the island where the shoreline makes a deep indentation. On Amey's right was the 3d Battalion, 2d Marines, commanded by Maj. John F. Schoettel. This battalion was to land on Beach R[SIZE=-1]ED[/SIZE] 1 on the western end of the north side of Betio. The beach was about 500 yards wide with a shoreline shaped like a crescent. In reserve for the regiment was the 1st Battalion, 2d Marines, commanded by Maj. Wood B. Kyle."

Now when reading this with your new knowledge on unit designations, does it make more sense?

 

I think it's starting to. It will truly begin to make sense once I start to try to model Marine units. (Which is on my to-do list.)

So A/1/4, rather than 1/1/4. My bad. Thought it was only the weapons company that would have been lettered in WWII parlance. But the Raiders cause trouble. The Raider Association lists Milton Solovic's unit as 1HQ, which I presume has something to do with "Raiders have to be different." I understand that the first four Raider Battalions were later rolled into a provisional 1st Raider Regiment, ere the Raiders were disbanded and rolled into the 4th Marines. (With 1st becoming 1/4, 3rd 2/4, 4th I believe 3/4 and 2nd becoming the weapons battalion. Couldn't just go one to one, but maybe Carlson's Raiders were especially suited to the weapons role, since he'd employed a different base organization, or what you would call a TOE, correct?)

Assuming that the HQ company became the early war D company then 1st Raider HQ would have become D/1/4? (And how they would have been designated When a part of the 1st Raider Regiment, which surely pissed off a fair number of people in both the Raider Battalions and the 1st Marines, I will ask later. But I begin to understand some of the enmity between the Raiders and the Corps at large: they were fighting not only over organization and eliteness, while increasingly doing the same jobs side by side, but also over what unit level to talk about and who gets to be 1st. Kind of like the school officially known as the University of Missouri at Columbia and the one formerly called Southwestern Missouri State University arguing in the state house about who should be called "Missouri State University" or MSU. Or perhaps "Mizz-You", if you slur it enough, but I digress.)

Just to be clear on the degree of my ignorance . . . there are typically 2 fire teams to a squad, 4 squads to a platoon (or possibly three in the Corps, given the whole triangle thing) and three platoons and a headquarters or support platoon of some kind to a company? Can I eek out a C- with that? (I should reorganize my company's worth of science-fiction infantry, er riflemen along USMC lines. Maybe that would help.)

 

Absolutely not...if you go to that WW2 Gyrene link I posted earlier it goes into greater detail as to the specific make up of platoons, squads and fireteams.
Generally speaking :
Fire team = 4 guys
Squad= 3 Fire Teams
Platoon = 3 Squads + Platoon leader + Platoon Sgt.

http://ww2gyrene.org/rifle_squad.htm