What Is Combat Arms in the U.S. Army: 7 Branches and MOS

In the U.S. Army, combat arms is the collective label for the branches whose primary mission is to fight the enemy directly on the ground. Seven branches carry the designation: Infantry, Armor, Field Artillery, Air Defense Artillery, Aviation, Engineers, and Special Forces.¹ Their soldiers close with and destroy enemy forces, seize terrain, and repel attacks. Every other branch in the Army exists to keep them supplied, informed, and moving.

The Seven Combat Arms Branches

Each branch brings a different capability. Some fight on foot, some from vehicles or aircraft, and some strike targets miles away.

Infantry

Infantry is the Army’s core ground combat force and the branch most people picture when they hear the term. Infantrymen fight on foot or from vehicles, conducting patrols, ambushes, raids, and assaults at close range. They operate in nearly every environment, from dense urban blocks to mountains to jungle. Light infantry units, including airborne and air assault forces, specialize in rapid deployment where heavier equipment cannot easily reach.¹ Mechanized infantry soldiers ride in armored fighting vehicles and work alongside tanks, combining dismounted skill with protected firepower.

Armor

Armor provides the Army’s fast, heavy-hitting ground punch. Crews operate the M1 Abrams main battle tank and Bradley fighting vehicles, using speed, firepower, and protection to break through enemy defenses and exploit gaps. Cavalry scouts within the branch conduct reconnaissance ahead of larger formations, finding the enemy so the rest of the force can maneuver against them.² Armor units historically lead offensive breakthroughs, and pairing tanks with infantry creates a threat that is very hard to defend against.

Field Artillery

Field Artillery delivers long-range indirect fire, striking enemy positions with cannons, rockets, and missiles from well behind the front line. Crews usually don’t see the targets they hit; they rely on coordinates passed from forward observers, scouts, or sensors. The branch’s nickname, “King of Battle,” reflects the role that accurate indirect fire plays in destroying enemy defenses before ground forces close in.³ Precision-guided munitions now let a single round accomplish what once required dozens.

Air Defense Artillery

Air Defense Artillery protects Army forces and critical assets from aerial threats, including enemy aircraft, helicopters, drones, and ballistic or cruise missiles.⁴ ADA soldiers operate radar and missile systems such as Patriot and the newer Integrated Air and Missile Defense platforms. ADA doesn’t seize terrain the way infantry does, but it fights enemy forces directly by shooting down incoming threats, which is why doctrine classifies it as combat arms rather than support.¹

Army Aviation

Army Aviation lets ground commanders leap over terrain, strike deep behind enemy lines, and move troops quickly across the battlefield. Attack helicopters like the AH-64 Apache engage enemy armor, fortifications, and personnel with missiles and guns. Reconnaissance aircraft scout ahead of ground units. Aviation counts as combat arms because its attack and reconnaissance elements directly engage the enemy, though the branch also handles transport, medevac, and logistics missions that fall outside the label.³

Engineers

Combat engineers blend construction skills with infantry-level fighting ability. They clear obstacles and mines so friendly forces can advance, build bridges under fire, emplace barriers to slow the enemy, and construct defensive fighting positions.⁵ The 12B Combat Engineer MOS is classified as a combat specialty with the same physical standards as infantry and armor soldiers.⁶ Engineers often operate right at the front, breaching enemy defenses with explosives so maneuver units can push through.

Special Forces

Special Forces, the Army’s “Green Berets,” are organized under the 18-series career field and classified as a combat arms branch.¹ Their missions include unconventional warfare, foreign internal defense (training partner-nation militaries), special reconnaissance, and direct action raids. Special Forces soldiers work in small, highly skilled teams that can operate independently in austere environments for extended periods. Entry requires passing a demanding selection and qualification course that goes well beyond standard combat arms training.

How Combat Arms Differs From Support Branches

The Army sorts its branches into three broad categories: combat arms, combat support, and combat service support. The distinction turns on how directly a branch engages the enemy.

Combat support branches provide specialized capabilities that multiply what combat arms units can do, without themselves being the primary fighting force. Military Intelligence gathers and analyzes information about enemy forces. The Signal Corps keeps communications running. Military Police provide security, handle detainees, and enforce order in rear areas. Chemical Corps soldiers deal with nuclear, biological, and chemical threats. These branches deploy alongside combat arms units and sometimes come under fire, but their core mission is enabling the fight rather than leading it.

Combat service support branches handle logistics, maintenance, medical care, transportation, and administration. Quartermaster soldiers manage supplies. Ordnance specialists maintain and repair weapons systems. Medical personnel treat casualties. Without these branches, combat arms units would run out of ammunition, fuel, food, and functional equipment within days. In practice the majority of Army soldiers serve in support roles rather than combat arms.

How Combined Arms Works

No combat arms branch fights alone. Army doctrine centers on combined arms operations, where infantry, armor, artillery, aviation, engineers, and other branches work together so each one covers the others’ vulnerabilities. An enemy who digs in against artillery gets overrun by infantry. An enemy who concentrates against infantry gets shattered by artillery. Armor stopped by obstacles advances after engineers breach the barriers. Attack aviation strikes deep targets that ground forces can’t reach yet.

This mutual reinforcement is the reason there are separate branches rather than one generic combat force. A combined arms task force built around an infantry battalion might include an attached tank company, a field artillery battery in direct support, an engineer platoon for obstacle breaching, and Apache helicopters on call. The commander synchronizes all of these capabilities against a single plan, creating problems for the enemy that can’t be solved by defending against just one type of threat. Getting this coordination right is what separates competent armies from dangerous ones, and it is the reason combat arms officers spend so much of their career training alongside branches other than their own.

What Holding a Combat Arms MOS Means for a Soldier

The label carries real consequences beyond job description. Fitness standards are higher, and certain pays only exist for soldiers who deploy or perform hazardous duties.

The Army replaced the Army Combat Fitness Test with the Army Fitness Test on June 1, 2025.⁷ All soldiers must score at least 300 total points with a minimum of 60 per event. Soldiers in 21 designated combat MOSs face a higher bar: a sex-neutral, age-normed combat standard requiring 350 total points with a minimum of 60 per event.⁶ Those 21 MOSs span five of the seven combat arms branches: Infantry, Armor, Field Artillery, Engineers, and Special Forces. The combat standard applies to every soldier holding one of these MOSs regardless of current assignment, so an armor crewman on a staff tour still has to hit 350. Failing to meet the standard can trigger administrative actions including barring reenlistment or separation. Active-duty soldiers had to meet the combat standard by January 1, 2026, and Reserve and National Guard soldiers in the same specialties have until June 1, 2026.

Combat arms soldiers do not automatically receive extra pay for holding a combat MOS. The additional money kicks in when they deploy to designated areas or perform specific hazardous duties. Hostile Fire Pay and Imminent Danger Pay provide up to $225 per month for soldiers serving in combat zones or areas where they face the threat of physical harm from hostile action.⁸ Soldiers who actually come under fire receive the full $225 for that month. Those serving in a designated imminent danger area without direct contact receive $7.50 per day up to the $225 cap.⁹

Hazardous Duty Incentive Pay applies to specific dangerous activities regardless of deployment location. Rates as of 2026 include $200 per month for Army static-line parachute duty (a common qualification for airborne infantry), $240 for military free fall, and $150 for demolition duty.¹⁰ Combat arms soldiers who earn multiple qualifying skills can sometimes stack more than one form of hazardous duty pay, though there are limits on combinations. Deployed soldiers also benefit from the Combat Zone Tax Exclusion, which exempts enlisted pay earned in a designated combat zone from federal income tax.

1
GlobalSecurity.org. Field Manual 3-90 Appendix A – Army Branches and Tactical Echelons
2
U.S. Army. Special Forces Candidate
3
Southern Oregon University. Army Branches – Section: Combat Arms Branches
4
U.S. Army. Air Defense Artillery Officer 14A
5
U.S. Army. Combat Engineer 12B
6
United States Army. Army Fitness Test
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U.S. Army Reserve. Army Introduces New Fitness Test for 2025
8
Office of the Law Revision Counsel. United States Code Title 37 Section 310 – Special Pay Duty Subject to Hostile Fire or Imminent Danger
9
Department of Defense Military Pay. Hostile Fire/Imminent Danger Pay
10
Defense Finance and Accounting Service. Hazardous Duty Incentive Pay Rates