Infantry MOS 0311, the basic rifleman, consistently sees the most combat of any Marine Corps military occupational specialty. This has held true across every major conflict the Marines have fought in, from Vietnam through Iraq and Afghanistan. Riflemen make up the largest share of ground combat forces, deploy most frequently to active combat zones, and spend the most time on foot patrols, security operations, and direct engagements with enemy fighters.
That said, several other MOS codes routinely see heavy combat as well, either because they operate alongside infantry or because their specific mission set puts them directly in harm’s way. The answer depends partly on the era and the type of conflict being fought.
Why 0311 Infantry Rifleman Tops the List
The Marine Corps exists to close with and destroy the enemy, and the 0311 rifleman is the most direct expression of that mission. Every Marine infantry battalion has hundreds of riflemen, and they are the ones clearing buildings, running patrols, manning checkpoints, and holding ground. During the wars in Iraq and Afghanistan, 0311s conducted thousands of dismounted patrols through areas saturated with improvised explosive devices and ambush positions. Their sheer volume of time spent outside the wire, combined with their numbers, means they absorb more enemy contact than any other MOS.
Other infantry MOS codes within the 03 field see comparable levels of combat on a per-Marine basis. Machine gunners (0331), mortarmen (0341), and assaultmen (formerly 0351) deploy with the same squads and platoons. They carry different weapons but face the same firefights. The reason 0311 stands out statistically is scale: there are far more riflemen than any other single infantry specialty.
Reconnaissance and Special Operations
On a per-capita basis, Reconnaissance Marines (0321) and Marine Raiders (formerly Critical Skills Operators, 0372) may face combat at rates equal to or higher than a typical rifleman. Recon Marines conduct multi-domain reconnaissance and surveillance, battlespace shaping, and special reconnaissance missions, often operating in small teams deep in hostile territory with limited support. When these teams make contact with the enemy, the engagements tend to be intense and at close range.
Marine Raiders, who fall under Marine Forces Special Operations Command (MARSOC), carry out direct action raids, counterterrorism operations, and foreign internal defense. Their deployment tempo during the height of the wars in Iraq and Afghanistan was extremely high, and their missions frequently involved deliberate raids on high-value targets. Because these units are small and selective, fewer Marines hold these MOS codes, but the ones who do often accumulate significant combat experience over multiple deployments.
Combat Engineers and EOD
Combat engineers (1371) are another MOS that sees disproportionate combat exposure relative to their numbers. During counterinsurgency operations, engineers were attached to infantry units specifically to deal with IEDs, breach obstacles, and clear routes. This put them at the front of patrols, often literally the first person to encounter a buried explosive. Explosive Ordnance Disposal technicians (2336) faced a similar reality, responding to IED finds and conducting render-safe procedures on live devices. The Marine Corps Combat Action Ribbon criteria specifically address IED exposure: direct exposure to an enemy-emplaced IED detonation, or taking direct action to disable one while close enough to be at risk from its blast, qualifies as active participation in ground combat.
Fire Support and Forward Observers
Fire Support Marines (0861) are frequently overlooked in this conversation, but they operate embedded with infantry squads and platoons. Their job is planning, calling for, and adjusting artillery, rocket, missile, and naval gunfire, as well as employing laser designators and guiding precision munitions onto targets. Because they must visually observe the target area to do their job, they position themselves at or near the front lines. They see the same combat the infantry sees, plus they carry the added responsibility of coordinating fires under pressure. In practice, a forward observer attached to a rifle platoon in Fallujah or Helmand Province experienced combat essentially identical to the riflemen around them.
Light Armored Reconnaissance
Light Armored Reconnaissance Marines (0313) crew the LAV-25, an eight-wheeled armored vehicle armed with a 25mm chain gun. LAR battalions are designed to screen ahead of the main force, conduct route reconnaissance, and provide security on the flanks. This scouting role means LAR units frequently make first contact with the enemy. During the initial invasion of Iraq in 2003, LAR units were among the first to engage Iraqi forces along major routes of advance. Their combination of mobility and firepower made them a constant presence in combat operations, though the nature of their contact differs from a dismounted infantryman’s experience.
How Conflict Type Changes the Answer
The type of war being fought shifts which MOS codes see the most action. In a conventional, force-on-force conflict like the initial invasion of Iraq, tank crews (1812, now deactivated under Force Design 2030), assault amphibian crews, and artillery Marines all saw significant combat. Artillery batteries were targeted by counter-battery fire and occasionally overrun. Tank crews engaged enemy armor and fortified positions at close range.
In counterinsurgency environments like Afghanistan’s Helmand Province, the picture changed dramatically. Combat became decentralized, and small-unit patrols by infantry, engineers, and their attachments bore the brunt. Vehicle mechanics, radio operators, and even administrative Marines sometimes found themselves in firefights during convoy operations, but the sustained, daily exposure to combat fell heaviest on dismounted infantry and the specialists embedded with them.
The Marine Corps’ ongoing Force Design 2030 restructuring has eliminated tanks entirely and reduced traditional artillery capacity in favor of long-range precision fires and smaller, more distributed units designed for maritime and littoral operations. This means future combat exposure patterns could look different from the last two decades of war, with a greater emphasis on anti-ship missile teams, unmanned systems operators, and reconnaissance units operating on small islands or coastal positions.
The Practical Takeaway
If you’re considering enlisting and want to know which MOS will put you closest to combat, the 03 infantry field is the straightforward answer, with 0311 rifleman being the single most common path. Recon (0321) and MARSOC (0372) offer even more intense combat exposure per deployment but require passing extremely demanding selection programs. Combat engineers, EOD, forward observers, and LAR Marines all see real combat regularly, especially when attached to or operating alongside infantry. Any support MOS can potentially see combat in a war zone, but these are the specialties where contact with the enemy is not an exception but a core part of the job.