///From the author: this is intended to be another "living document" series, similar to the Ships of the Line post, and as the name suggests, it will show off bits of lore relating to the uniforms and equipment of the various factions in the Frontier Wars which make up the background of the eponymous segment of the Spacers Saga universe
The Interplanetary Defense Corps
Uniforms:

Notes:
The standard-issue combat duty uniform of the Spacer Corps as of 2379 is the Personnel Combat Utility System (PCUS, pronounced “pieces”), which was adopted in the early 2340s as part of the massive modernization program initiated by Aerospace Command (AEROCOM) in the mid- to late 2330s as a result of lessons learned during the Jovian Crisis (2315-2327) and the early years of the long Draconist Crisis which followed.
By the start of the Zharan Uprising in 2343, there were three main uniform varieties in use by the IDC Fleet and Infantry forces, each of which was designated SOCAM (short for “Standard Operational Camouflage”) with a numeric designation of I, II, or III to delineate the different versions. One of them was considered the standard camo pattern of FLEETCOM operations, and is worn almost exclusively by spacers on operations aboardships and by those in garrison at groundside fleet facilities, including bases and ports of call.
The other two SOCAM varieties are designed for use by spacers of all other Combatant Commands across the Spacer Corps, with a version meant for use in arid environments (i.e. Mars, Titan, and so on) and another meant for use in temperate environments such as Earth and the various “grav balloon” habitation zones of the Main Belt and elsewhere. These two varieties of SOCAM are also worn by INFORCOM spacers in garrison.
The final two variations of the PCUS uniform shown here are SPECAM (short for “Special Operations Camouflage”) I and II, which, as the name suggests, are intended for use by members of the Spacer Corps’ elite Special Operations Command (SOCOM). Personnel wearing this uniform in garrison or in other non-combat locations are typically seen wearing the Black Beret of the special operations forces, unless they are of a specialized subcommand which wears a different color, and are highly respected by other spacers.
Equipment:

M93A2 Combat Applications Weapon System (CAWS)
Caliber: 5.3 x 37 mm SHREDDER (semi-caseless, optimized for armor piercing capabilities)
Dimensions: 64.1 (L) x 7.1 (W) x 22.5 (H) centimeters (in standard configuration)
Weight: approx. 2.8 kilograms fully loaded (approx. 2.1 kg unloaded)
Barrel length: 27.4 centimeters (1:16 rifling twist, with magnetic coil enhancement)
Feed system: double-stacked horizontally-fed 42-round detachable box magazine
Cyclic rate of fire: 900-1300 rounds per minute (gas cycle control-enabled)
Effective range: approximately 400 meters (maximum range for use - approx. 1 kilometer)
Standard sights: 1x magnification M193A3 holographic battle sight system
Backup sights: built in backup iron sights, adjustable to 200 meters
Additional features: vertical foregrip w/ integral snap-out bipod; built-in data readout
Primary manufacturer: the Rakshak Arms Corporation (based on Mars)
Notes: another entry in the SPACER 300 program (named for its intended completion date of 2354, the 300th birthday of the Spacer Corps) which AEROCOM initiated in the 2330s, the M93 was actually designed over twenty years earlier for entry in the Advanced Combat Weapons Initiative to replace the aging fleet of M71 rifles and carbines which had been produced beginning in the 2270s, and designed as far back as the immediate aftermath of the Mars-Titan War (2253-58). The program, although ultimately shelved by AEROCOM due to concerns arising from the necessities of the Jovian Crisis, did produce a worthy design, the XM89, which would be refined over the 25 years which followed the program’s cancellation into the XM93, a flawed but ultimately workable version that was finally fielded as the M93 in 2342. The flaws in this initial design, many of which centered on the rifle’s attempt to marry semi-caseless ammunition with a magnetically accelerated firing system, were gradually worked out, and by the introduction of the A2 variation in 2368, the weapon was considered a worthy tool for use by any spacer in the Fleet
The Armada of the Free Worlds / Zharan Armed Forces
Uniforms:

Notes:
First fielded in 2328 as part of the Alliance of Free Worlds’ emergency military activation program of 2327-2332 (the first “five-year plan” the Alliance ever initiated), the "ARMADAPAT" system is three-tiered. The basic "Fleet Grays" are usually worn printed on jumpsuits, as are Fleet duty uniforms in the IDC and ZAF. These jumpsuits are designed to be worn as a primary layer beneath an EVA suit, and are therefore optimized for thermal protection and defense against air leakage and other threats to life and limb in the vacuum.
ARMADAPAT 2 and 3, the Arid and Temperate camo patterns, are worn on garrison uniforms or on combat suits issued for deployments to various biomes. It is worth noting that the Temperate version of ARMADAPAT has a reputation for denoting Special Forces status, as most Alliance ops which would take their troops to Earth or the Belt orbitals are deniable in nature, and therefore involve the Special Force.
Unlike the Spacer Corps, however, the Armada does not delineate uniforms between different combatant commands, and abandoned the IDC’s use of color-coded berets to identify members of these different groups as soon as it was formed. As an organization built upon the notion of equity and brotherhood between all of its citizens, the Alliance sees these distinctions between members of its military as a basic affront to their sensibilities, and as a result their military leadership chooses to eschew even specialized unit patches.

Notes:
First fielded beginning in the early 2350s, only a few years after the Zharan Collective successfully split off from the rest of human society, the Zharan Armed Forces based its standard uniform system largely upon the Armada's camouflage system. Also a three-tiered camouflage system, with the IDC camo reporting names of Alpha, Beta, and DeltaPat, this system is typically printed on duty uniforms, coveralls, or as standard day-to-day service uniforms, or on the external surface of combat armor and/or EVA suits.
It is worth noting that the example of AlphaPat shown here was obtained by SOCOM operatives working behind the lines in the outer system in the mid- to late 2360s, as part of operations intended to establish a base of knowledge about the new Zharan Armed Forces’ strength and disposition. The other two examples you see were obtained after the Collective entered the Frontier Wars on the side of the Alliance, which afforded SOCOM the opportunity to recover them in regular combat operations. The Spacer demonstrating the three examples wears contact lenses and face paint to simulate zharan facial distinctions.
On that note, another important fact about the zharans (and one vital to identifying a zharan’s background) is their predilection for facial markings, which usually denote social delineation. In this case, the red eye stripes and chin chevron denote the warrior caste, with some intelligence suggesting that this is meant to be symbolic of zharan warriors being "up to the eyes" in the blood of their enemies. Since zharan soldiers are notoriously tight-lipped when captured, however, this rumor remains unsubstantiated as yet.
Equipment:

G31 Standard-issue Armada Battle Rifle (SABR)
Caliber: 6.8 x 54 mm Thunderclap (optimized for anti-personnel capabilities)
Dimensions: 68.6 (L) x 6.6 (W) x 28.2 (H) centimeters (in standard configuration)
Weight: approx. 3.7 kilograms fully loaded (approx. 2.6 kg unloaded)
Barrel length: 45.9 centimeters (1:14 rifling twist, with magnetic rail built in)
Feed system: double-stacked vertical 30-round detachable feed system
Cyclic rate of fire: 700-800 rounds per minute (comes standard with 3-round burst)
Effective rate of fire: approximately 600 meters (maximum range for use - 1200 meters)
Standard sights: 1-7.5x magnification Type 34M2 Enhanced Combat Optic
Backup sights: built in backup iron sights, adjustable to half a kilometer
Additional features: removable handguard to allow underbarrel attachments
Primary manufacturer: Steyr-Tekiyo Military Arms Corporation (based on Titan)
Notes: the design which ultimately became the G31 entered development in the late 2290s, but remained in limbo for over twenty years due to the instability of the Jovian Crisis and the civil war it spawned on Titan. When the Alliance of Free Worlds was incorporated from a union of secessionist outer system republics in 2325, the first thing they did was initiate a massive program of military spending which was intended to bring the new Armada of the Free Worlds up to a position more on par with the Spacer Corps. One of many programs which cropped up as part of this first five-year plan was the development of a new standard-issue weapons system, which settled on a Steyr-Tekiyo Corporation design which had been shelved for over fifteen years. The finalized design was adopted and first produced in 2331, hence the designation of G31, and has seen use across the many trouble spots of the mid-24th century, including the Draconist Crisis (2332-2348) and the Frontier Wars (2361-2371). As of 2379, the G31 has been in use for nearly fifty standard years, and owing to its exemplary service record and good reputation, could be in use for another fifty
More to come, when it's ready...
These are so great. You should do one just on the Zaharans!
Some notes on this post:
The content above would not be possible without templates sourced from three artists on DeviantArt: TheGrandAdmiralJoey, whose was work was the basis for the Alliance uniforms; EmperorGrieferus, whose uniform designs were the template for the Alliance uniforms; and DontForgetJeff, whose work provided a template for the Zharan uniforms