'Twas a joke, my friend, nothing more. Hence the wink emoji.
I am more curious as to, in the name of this thought experiment, sounds "Trekish." We have Crewman, so you could have Troopman, or Guardsman, but I guess I find the whole "Trekish" thing curious since we have use of US NAVY lingo across the board, especially in TOS. So, I want to respect the limits put down but they feel very arbitrary at times.
Nah I got it, just elaborated.
Some of what i'm going for with "Trekish" is somewhat arbitrary, as it's hard to strictly define and articulate an aesthetic. Things need to "feel" right. That's why I was hoping for a bunch of spitballs... some feel right, some feel wrong, but it's hard to pinpoint exactly what i'm looking for.
This whole thing gets more complex when we take into account the entirety of the Trek timeline. I think the aesthetic choices can move around... in the TOS/Movie-Era, I think we can go a bit more overtly militaristic than we would in the TNG+ Era. In an initial rough draft of this idea, I actually did have this organization begin it's like as "Starfleet Marine Corps." in the early Federation era and eventually morph into something less overt post-Khitomer Accords. As I was developing the political atmosphere of the birth of the Federation, things changed a bit.
I've always liked the name 'Starfleet Marines'. Simple, logical, efficient.
I was batting around simply "Starfleet Marines", and ended up with the compromise that it's not the organization's official name... but most people within Starfleet tend to just call them "Starfleet Marines".
and of course a different rank structure, but they are still Starfleet, and would possibly be rather hurt if they were ever called a separate force.
In this context, they *ARE* still Starfleet... just... a different branch of Starfleet. They exist under Starfleet Command, it's just separated the space fleet ("Navy") from ground forces.
As for the officer ranks: I see them as having eliminated the rank of Marine Captain (so as not to be confused with the naval rank), moving the two Lieutenant grades up (so you would go straight from 1st Lieutenant to Major), and adding a new rank - "sublieutenant", maybe? - as their equivalent of Ensign.
A part of me does like Sub-Lieutenant, as a nod to Vulcan involvement in its creation.
You also have colonel West from ST 6 as well.
Colonel West is one of the biggest reasons why I specifically wanted this organization to be a separate branch of Starfleet. I wanted the different rank structure, but I didn't think it made any sense to just have two different rank structures in the literal same organization.
In Star Trek Enterprise, there was a branch of United Earth Governments that acted similar to Marines - the Military Assault Command Operations - or MACO. https://memory-alpha.fandom.com/wiki/Military_Assault_Command_Operations
I have them account for here. They make up a good chunk of the initial personnel of the branch when it's created. In my reboot here, I did change the name though. It stands for (United Earth) Marine Command. MA-CO.
Actually the 21st/22nd centuries are the most fleshed out part of this so far, just beyond the scope of this particular thread.
In the Star Trek Hunter trek-verse, I maintained the old nation states as members of United Earth Governments (along with member colonies), each of which maintain military forces for homeworld and homeland defense. All of these forces are under the auspices of the United Earth Governments, which, in turn, is a founding member of the Federation.
So when Marines are needed, they are actually United States Marines (which developed an elite space-bound division known as the Space Hounds). Several stories in the Star Beagle Adventures series feature the Space Hounds, who wear a beagle patch on their uniforms as an identifier.
It's a neat idea, and my universe here does mirror some of that. On the Federation level, member worlds absolutely do still operate their own military forces, or at least can if they so choose. To get into the real nitty gritty of it... I also have old nation states of Earth existing... although they're a nominal existence and really just serve as administrative districts within United Earth and traditional/cultural groupings. The actual "governments" of those nations mostly exist to send representatives to the United Earth Parliament.
In this world, individual nations militaries existed in some form until sometime just shortly after the creation of the Federation, but really lost prominence in favor a United Earth military in the late 2150's. My ENT-Era actually has Earth Starfleet in direct competition with the US Space Force, both trying to assert dominance over Earth's space assets. Starfleet wins out, and by 2156-7 United Earth passes legislations to consolidate Earth's militaries into a single force. It takes about a decade for everything to fully transition, but realistically by the time the Federation comes into being, the individual national militaries of Earth are shrinking rapidly, and almost all of the space assets have been absorbed into Starfleet or the much smaller Earth Defense Force fleet.
The legacy of the USMC does live on in some form, as in this world it was very much the basis for United Earth Marine Command, and MACO's continue to exist within the EDF all the way through the 24th century. Earth only keeps a smalls standing force, preferring to send the vast majority of its support to Starfleet, but they exist.
Going on a tangent here, we do get some interactions with the various member worlds military groups. By the time we get to the Dominion War, I have a story arc about Starfleet getting pretty badly beaten up and Sisko being tasked to bring the Andorian Imperial Guard fleet into the active fighting. The Andorians had decline to commit forces to the frontlines, upset with how Starfleet was handling the war and argued due to Starfleet's incompetence, they needed to retain all of their assets for defense of Andor. Eventually, the Dominion stages an attack on Andorian territory and the Andorian fleet can't deal with the coordinated attack. Starfleet comes into the save the day, along with support from the Vulcan Expeditionary Fleet. That was enough for the Andorians to finally fully commit their home forces to the war effort.