UNSC Army

The UNSC Army is a branch of the UNSC Defense Force primarily responsible for land-based military operations.

Background
Little is known about the UNSC Army, due to the fact that the Army is a land-based fighting force, and thus does not operate alongside the UNSC Navy as often as the UNSC Marine Corps does. What is known is that the UNSC Army uses different equipment from the Marines, examples of different equipment being the M6J Carbine, the MA37 Individual Combat Weapon System, and the M392 Designated Marksman Rifle, in contrast to the MA5B/MA5C assault rifles and BR55 Battle Rifle in use by the Marines. Soldiers of the UNSC Army wear the UNSC Army Battle Dress Uniform.

Role
It is known that the UNSC Army frequently patrols colony planets, but little is known about any operations they have participated in. Known operations include the Battle of Reach, where Army units assisted SPARTAN Noble Team in defending the planet, the Battle of Earth, where an Army unit tried to aid Marine forces in New Mombasa and was annihilated in the attempt, and the Battle of Mare Erythraeum on Mars, where Colonel James Ackerson led an unknown number of Army forces against the Jiralhanae commander Lepidus and his army. Unlike the Marines, who take offensive action against the enemy from naval vessels, the UNSC Army launches offensive operations from land bases against land based targets and are used in capturing and establishing UNSC-held territory.

The UNSC Army supposedly also takes a large role in training colonial militia. While Marines have been known to train colonial militia, such as that of Harvest, it is far more likely that the Army, as the defensive arm of the UNSC, would normally take charge of maintaining militia forces.

It is also unknown what role the Army played in Operation: TREBUCHET and what actions they were apart of, although TREBUCHET might have been a Marine exclusive counter-terrorism operation.

There are also a number of Army special forces groups. The only known such group is 3 Charlie, a reconnaissance team which, along with Noble Team, is a part of Special Warfare Group Three.

Trivia

 * The helmets worn by Army soldiers appear to be similar to those worn by the Marines; and may be the base of the MJOLNIR Military Police armor permutation in Halo: Reach's Armory. Additionally, their shoulder pauldrons are identical to the GUNGNIR shoulder pieces.
 * It's interesting to note that female Army soldiers have hair descending down from their helmets, possibly showing that the Army is more lenient with its rules on hair length compared to the Marines (where all female Marines seem to have crew cuts).
 * The UNSC Army makes its in-game debut in Halo: Reach, in which UNSC Army soldiers, Marines, and ODSTs have their own service tags showing their name and rank. Some of them are named after Bungie and Roosterteeth employees.
 * The Halo: Combat Evolved Manual, states that UNSC Marines &quot;They're the best of the best, but they're only human.&quot; This is odd due to the fact that Army Troopers in Halo: Reach are far more skilled in combat than UNSC Marines, for example, 8 Army Troopers Privates armed with 5 Assault Rifles, 1 DMR, 1 Shotgun and 1 Sniper Rifle can - On Normal Difficulty - hold of 5 waves of Covenant infantry, each wave consisting of 3 Grunt Majors, 2 Jackal Majors and 3 Elite Ultras, with a total of 25 Grunts, 10 Jackals, 15 Elites. The same number of Marines armed with the same armament would never survive in the same situation. This could be due to the fact that the gaming engine was upgraded for the A.Is in Halo: Reach
 * Oddly, if you listen closely to the transmissions and dialogue in Reach, the UNSC Army is never mentioned by name. The soldiers are called troopers, but there is never a definitive mention of the branch.
 * The UNSC Army in campaign is often confused for the UNSC Marines due to the fact Marines almost always accompanied the player in previous Halo games. However, the UNSC Army is entirely different from the Marines.
 * Strangely, sometimes with the IWHBYD Skull an Army Trooper will say, if the player stares at him long enough, that he wonders if he were a Spartan and how "cool" it would be able to beat any Marine. This could be scripting error of the Army Trooper accidentally referring to himself and comrades as Marines or this could imply a rivalry between the UNSC Army and Marines somewhat like the ODST rivalry with Spartan II's