What is an “Expeditionary Force?” No, Really, What is It?
For a Pioneer nation like America, built on exploration and a seemingly endless frontier, the romance of expeditions is part of our national psyche. The term “Expeditionary Force” sounds cool, as it evokes feelings of adventure and risk-taking in far-away places. Expeditionary forces are comprised of tough, competent men who travel light in remote areas, and rely on their wits to survive and win in unfamiliar environments. Thus, it’s only natural we want to call everything our military does abroad an “Expeditionary Force.”
However, not everything is an “Expeditionary Force,” simply by virtue of being overseas, as JP 3-0 currently defines it:
Expeditionary Force: An Armed Force organized to achieve a specific objective in a foreign country.
Defining it this way turns every war America has fought since 1815 into one fought by an “Expeditionary Force,” regardless of the vast differences between the campaigns. This broad official definition does not distinguish between Pershing’s punitive chase of Pancho Villa in 1916, Patton’s 3rd Army in 1944, or the SOF-dominated Invasion of Grenada in 1983. These three campaigns had vastly different objectives, organizations, and methods, with few similarities besides being fought in a foreign country, yet JP 3-0 would call them all “Expeditionary Forces.” A more specific definition is warranted to avoid confusion, particularly when planning a campaign or developing a permanent force structure.
There are three distinct styles of modern warfare, based on missions and methods, and their principles have not fundamentally changed since the 1970s.[i] These are: Continental Warfare, Expeditionary Warfare, and Insurgency/COIN. Although distinct, they are not mutually exclusive, and blending 2 or more at the strategic level[ii] should be the definition of “Hybrid Warfare:”
Proposed definition for Hybrid Warfare:
A Style of Fighting that blends elements and strategic end-goals of two or more styles of Modern Warfare: Continental, Expeditionary, and/or COIN.
Understanding the differences between the three is crucial to avoid using the wrong tool for the job. We will start by describing COIN and Continental warfare, to show what Expeditionary Warfare is not, and then describe what Expeditionary War is.
Insurgency/COIN is the most familiar to us at the moment, as we are engaged in this type of Warfare in the Middle East and Africa. This is the most political form of warfare, and lacks large-scale maneuvers above battalion level. Instead, both insurgents and COIN forces fight at the squad-, platoon-, and company-level, each trying to annihilate the other, and thus chip away at the other’s forces over time. Both sides’ tactics seek annihilation, but their operations and strategies are both attritional in nature. COIN is a style of warfare that is driven almost exclusively by strategy and tactics, rather than what happens at the operational level. Despite actual combat taking place on a small scale, and the higher proportion of sociopolitical actors at the strategic level, COIN is manpower-intensive. It is normal to require as much as a 20-to-1 advantage in numbers to effectively wage COIN before factoring in non-military needs. Despite the need for overwhelming numbers, however, the equipment requirements per capita are the smallest out of any form of warfare. COIN from a military perspective is a war of snipers, mortars, airmobile/riverine light infantry, Gendarmes, and mine-resistant armored gun trucks. Swarm tactics, vertical envelopments, and saturation of regions with platoons are its usual tactics. In Vietnam, the United States effectively countered the guerrilla threat through the Marine Corps’ Combined Action Companies, backed by Aero Rifle Platoons acting as a QRF, and this model will continue to be valid for the foreseeable future. Beyond this, all other efforts are sociopolitical in nature.
For future COIN campaigns, the author would recommend assigning the entire Marine Corps to the task. Not only does the Marine Corps have a proud history of Counterinsurgency in both Vietnam and the Caribbean, but COIN’s radically different requirements from Continental Armies and Expeditionary Forces means it would be institutionally better to have a separate branch of the military dedicated to the task. In theory, this separate branch could be the Army, while the Marines tackle continental warfare or expeditionary warfare, but this would require tripling or quadrupling the size of the Marine Corps, and would require more effort than switching to a COIN force (which the Marines are already properly-sized for).
Thus, the official definition of COIN is sufficient and does not need to change:
Counterinsurgency: Comprehensive civilian and military efforts designed to simultaneously defeat and contain insurgency and address its root causes.
The second style of Modern Warfare is the Continental War. Continental Wars are fought in geographically vast theaters, and normally are wars with unlimited political objectives (i.e., to totally destroy or overthrow the enemy). Although small unit tactics are no less important compared to COIN, Continental wars are defined by what happens at the operational (Regiment/Brigade,[iii] Division, and Corps) level. Continental wars almost always utilize one or more Field Armies, containing multiple Corps apiece, and their operations involve multiple Division/Corps thrusts in parallel across an opponent’s frontage and throughout his strategic depths. Unlike the tactical level, in which battles are decided at decisive points, operations are greater than the sum of their parts. A good analogy would compare the difference between tactics and operations to that between a pinpoint and a square.
For this reason, traditional continental powers (China, Russia, Germany, Persia, Zululand, etc.) historically favored operational-strategic encirclement, as the vast theaters give them ample freedom of maneuver and their armies possessed the necessary manpower and mobility. Naval/amphibious tactics also follow this trend, and so Island-hopping campaigns can be considered a variation of continental warfare. Other traditional solutions, particularly for those fighting at a numerical disadvantage, include elements such as long-range gunnery and armored protection. In the modern age, the two wars which best illustrate continental warfare are the 1973 Yom Kippur War and the 2014 war in Eastern Ukraine. Both wars were characterized by:
- Hyper-violent combat at close range and long range, both in open plains and fortifications/urban combat[iv]
- Mass employment of GR-AMM, including handheld rockets
- The dominance of heavily armored vehicles, both tanks and troop carriers
Heavy Tanks, in particular, are dominant on the modern continental battlefield due to their firepower, protection, and mobility. Any continental army must therefore possess a robust armor backbone supported by equally-protected mechanized infantry (preferably mixing them down to the company level), and backed by an all-inclusive array of armored self-propelled artillery, tactical nuclear artillery, EW platforms, and Cyberwarfare hubs. Heliborne or dismounted light infantry armed with handheld antitank munitions, heavy machine guns, mortars, and MANPADS are useful in dense/difficult terrain, but must be experts in concealment, deception, and entrenchment due to their vulnerability to massed artillery strikes (this also applies to lightly-armored vehicles like the Bradley and Stryker). Both artillery and air power are vulnerable to counterbattery/AA fire, and so must emphasize long-range standoff combined with either speed or protection. For Artillery, armored self-propelled guns are mobile enough to shoot-and-scoot, while also able to survive hits; towed artillery has neither advantage. Aircraft generally lack thick armor, and must therefore use EW and supersonic speed to evade attacks. Electronic Warfare and Cyberwarfare are not only necessary for impeding an enemy’s communications and targeting systems, but also to ward off drones, whether they are used singly or in swarms. Precision munitions and cluster munitions are particularly advantageous and should therefore be ubiquitous.
In short, continental armies are melting pots when it comes to tricks, tactics, ideas, and equipment. The main drawbacks are that they do not travel light, aren’t cheap to build/maintain, and must remain tethered to supply lines. Optimization of cost-effectiveness is always a step in the right direction, but the temptation towards “if it isn’t light, it ain’t right” in continental forces must be avoided. Light forces in continental wars have extra mobility compared to heavy forces, but not everybody surrenders when their maps tell them they’re surrounded. Against an opponent who stands his ground (or attempts a breakout), armies comprised solely of light forces must possess an overwhelming numerical advantage in order to compensate for their lessened killing power, and the losses which would be sustained are higher than America is willing to pay. Instead, light and heavy forces should be paired together, beginning at least at the brigade level. Improvements to the Teeth-to-Tail ratio should focus on items such as improving the quality of logistical formations so that the Army can afford to either shrink them, have fewer of them, and/or shift them to divisional level. Other options include improving fuel efficiency, mechanical reliability, and/or electrical (i.e., batteries and sensors) longevity in vehicles/aircraft to minimize the number of fuel stops and maximize loiter time. A Continental Army is built to survive a tactical slugging match, and America should double down on its ability to outlast her opponents after surviving the first round.
Since this term does not exist in JP 3-0, the following new term is proposed:
Continental Army: A ground force, normally larger than one corps, organized to fight wars with unlimited objectives, particularly those in urban areas and/or geographically vast theaters. Continental Armies use a mixture of light and heavy mechanized units to simultaneously wage combined-arms warfare at the tactical, operational, and strategic levels.
Finally, we come to Expeditionary Forces. A true Expeditionary Force is not defined by its equipment, but by its mission: long-range operations which are not connected to a continuous supply line. Historically, expeditions (both civilian and military) began where civilization, and more importantly its infrastructure, ended. The lack of continuous resupply meant that expeditions were numerically small and Spartan, as they had to carry everything themselves. The 19th-Century British Army is the best example of this in the military, as their campaigns in Africa and India routinely led them hundreds of miles from their supply bases. A typical British Expedition consisted of only a handful of battalions supplemented by local levies, and tactics often consisted of moving to a strategically important position that could be defended, entrenching, and repelling counterattacks through volley fire (to conserve their limited supply of ammunition) and artillery. Campaigns were short, normally lasting less than a year, and would be considered failures if no decisive results were achieved.
In the modern age, continental wars rely on constant resupply, and COIN forces deal primarily with convoy ambushes, rather than being threatened with their total severance. This trend continues when discussing island campaigns in the Pacific, as supplies brought by the Navy are still a regular occurrence. A true expeditionary force, by contrast, would voluntarily go beyond the reach of resupply (i.e., other than purely airlift) to fight. Such a force would use conventional tactics like a continental army, but would fight in geographically small secondary theaters with terrain unsuitable for mechanized warfare. A good example of what an Expeditionary Force would look like comes from a missed opportunity in the early stages of the Vietnam War: When the Ho Chi Minh Trail was first built, it passed directly across the 17th Parallel DMZ. President Ngo Dinh Diem successfully cut the trail, and in response the North Vietnamese moved it across the border into Laos, which was too weak to resist infiltration. Before his assassination, Diem asked the United States to consider an intervention in Laos to cut the new trail as it passed through the Laotian panhandle. This plan went through multiple revisions,[v] but consistently called for 4 divisions to establish blocking positions in the difficult mountain terrain, with a particular aim of thwarting wheeled traffic. Blocking wheeled traffic would prevent heavy weaponry from traveling south in any great quantity,[vi] and foot patrols (possibly supplemented by SOF/local Montagnard allies) would tackle everything else. The force could be resupplied via Route 9, which contoured the region perfectly and was designed to be passable under monsoon conditions. Nor could the communists bypass these positions by wheeling further west, as they would add another 500 miles to the journey and pass into Thailand, which was militarily stronger, and more anti-communist, than Laos.
Route 9 Today
At first, these 4 divisions and this lifeline may seem to be contradictory to the idea of a true expeditionary force; too large of a force and too constant a resupply route. Yet 4 divisions would be far too small to carry the war beyond the Laotian panhandle or conventionally invade North Vietnam, which is consistent with the strategically defensive posture America and South Vietnam both favored. It would, however, be too large to suffer the fate of the French at Dien Bien Phu.[vii] The Expeditionary Force would be operating in extremely difficult terrain that combined both mountains and trackless jungle suitable for light forces rather than mechanized warfare. Their lone supply route could potentially be cut at any time by Communist infiltration, as would happen at the start of the siege of Khe Sanh in January 1968. Furthermore, their purpose was to seize defensible ground through which the Ho Chi Minh Trail had to pass, entrench, and then repel communist counterattacks and cut their supply routes- just like the 19th-Century British. It was a far cry from a continental campaign aimed at overthrowing the government in Hanoi, and even farther from a counterinsurgency effort.
So in the Modern Age, a true expeditionary force would possess the following attributes:
- Light, non-mechanized Forces
- Small formations, no larger than one corps
- Infrequent and/or irregular resupply
The best candidates for this type of warfare are not amphibious forces, but paratroopers. Amphibious troops, even when seizing limited objectives, can still count on the navy for resupply and comparatively unimpeded strategic mobility, and therefore fight as a miniature continental army. Air assault troops are better-suited to continental warfare because helicopters are more agile compared to parachute drops, while their disadvantages (compared to airplanes) in fuel consumption and range are well within the capacity of a continental army’s logistics and mechanized reach. Paratroopers, by contrast, have to travel light because of the weight limits of aircraft (both for the initial drop and airlift resupply), and are meant to be surrounded and partially isolated once they land. Many unique features of paratroopers have become less important in continental warfare, but remain viable for expeditionary warfare. Paratroopers can be deployed anywhere in the world within 18 hours. They can land in one large wave, rapidly overrunning enemies through the use of speed, and then consolidate and dig in. For establishing blocking positions or rapidly seizing key terrain, they are ideal.
So the following new definition for “Expeditionary Force” is proposed:
New definition: An armed force, no larger than one corps, organized to achieve specific, but limited and often defensive, strategic goals in a foreign country. Their missions will normally take place in difficult, restrictive, and/or low-acreage geography, and they thus make use of lighter units such as paratroopers and air cavalry.
Having established the distinctions between the three types of modern warfare, the next natural question is their organization. As mentioned previously, the author recommends assigning the Marine Corps to cover counterinsurgency, and the Army to continental warfare. For an expeditionary force, the easiest method is to use the Army’s existing structure with a few modifications.
I and III Corps would fully embrace continental warfare, with I Corps keeping its Pacific focus[viii] and III Corps focusing on open warfare and inaugurating the Army’s first dedicated urban combat school. Both corps would possess at least one specialized riverine brigade and one mountaineer[ix] brigade, and I Corps would retain at least one jungle warfare division (For Arctic warfare, the author would recommend creation of a separate Corps in Alaska, due to the distinct logistical requirements of arctic terrain). This arrangement permanently preserves Continental warfare, including its urban and amphibious variants, from an institutional perspective and each Corps would provide a mecca for theorists and experimentation. It also requires only a change in mindset and allocations, rather than inventing new equipment. Should a continental war break out, then these corps can swell organically into a field army, rather than building said field armies’ orders of battle from scratch.
The XVIII Airborne Corps would become America’s Expeditionary Air Corps (EAC), comprised of 3 Paratrooper divisions and 3 Air Assault Divisions. This arrangement is not arbitrary; the paratroopers are intended for establishing blocking positions and semi-static warfare, while the Air Assault Infantry (“Dragoons”) would play a supporting role as a mobile reserve. The paratroopers are the anvil, the air assault troops would be the hammer. Possessing three of each in peacetime allows the EAC to mix and match, depending on the optimal ratio, for an upcoming expedition; for example, one mission may only require 1 paratroop division for blocking positions, but three air assault divisions for patrolling the gaps. The reverse is equally probable. Thus, the EAC’s organization is highly flexible and can be adapted to most situations. Since few expeditions will require the use of all 6 divisions at once, the possibility of 2 or even 3 expeditions occurring at once is a real possibility.
All of the EAC’s aircraft, whether they be for drops, airlift/resupply, or Close Air Support, should be organically integrated into the Divisional or Corps order of battle, and not attached temporarily from the Air Force. Bifurcated parallel chains of command can provide useful redundancy in the strategic defense, but this is a liability in the offense/tactical level. Organic integration reduces friction within the chain of command, increasing responsiveness, and if the Air Force continues its quixotic quest to get rid of the A-10 Warthog, then those wings can find a new home in the EAC. The divisions would also do away with the brigade, returning to the Regimental Combat Team, and consolidate all support units under divisional control to become less “tail”-heavy compared to continental or COIN armies.
The EAC’s engineers and artillery would be placed in the Paratrooper divisions, while the Air Assault Dragoons would rely on mortars and helicopter gunships in lieu of howitzers to remain highly mobile. All equipment carried by the EAC’s paratroopers and Air Assault troops should be air-droppable and man-portable since they will operate in areas that may or may not have airfields or roads. Each division would necessarily be restructured to ensure that there are sufficient porters and/or riflemen to carry all of its own gear on road marches without requiring vehicles. Helicopters are extremely useful in moving men and supplies quickly through broken terrain, but the expedition’s limited supply of fuel (and/or bad flying weather) may temporarily force the troops to carry everything on foot. The air assault infantry’s mobile patrols will always get first priority for fuel, and the paratroopers’ semi-static defenses will reduce consumption as much as possible on their end. Having every item man-portable (or capable of being broken down into man-portable pieces) guarantees that it’s light enough for paratroopers, and if the Expedition loses its vehicles it’ll be slowed rather than stopped dead in its tracks. Here, the slogan “If it ain’t light, it ain’t right” does apply. Mortars will be of paramount importance in expeditionary warfare, even more so than regular artillery, and a 1:1 ratio of 60-mm mortars to rifle squads is to be expected at a minimum.
Training in the EAC should place a high emphasis on marksmanship, both in semi-automatic and fully automatic, and include both SERE and mountain warfare training. All personnel, not just the infantry, should be held to higher marksmanship standards than in continental armies, since their ammunition resupply is less regular, and their artillery support smaller per capita. In many respects, it should emulate the legendary pre-WWI British Expeditionary Force (BEF)[x] standards of marksmanship, in which 600 meters was considered “close range.” This high standard was inspired by the Second Boer War, which was fought as a continental war in a trackless frontier environment. The Boers conserved their limited ammunition supply by emphasizing individual marksmanship, rather than through volley fire, and it proved to be so effective the British Army eagerly copied it after the war. The BEF would ultimately rely on this same tactic when it faced the brunt of the von Schlieffen Plan in 1914, and the power of skilled marksmen did not disappoint (the 1914 campaign also illustrates many of the limitations of expeditionary forces in continental warfare). Tactics have since changed, but this merely adds the necessity of training individuals and crew-served weapons to shoot accurately on fully automatic, rather than lowering semi-automatic standards. Training a corps to this higher standard will also aid the development of the Army’s Designated Marksmen Program, as it will provide a raison d’être for its continued existence in peacetime/drawdowns, feedback on its tactical and institutional effectiveness, and a career pipeline for instructors. All EAC personnel should graduate the Army’s SERE school and Mountain Warfare school, since they will need many of the skills historically reserved for Long-Range Reconnaissance Patrols and non-mechanized armies. Expeditionary forces will often fight in mountainous terrain, and SERE methods will be essential for any paratroopers who are dropped on the wrong drop zone, air assault infantry whose choppers are shot down, or if the Expeditionary Force is overrun (God forbid) and must exfiltrate the theater on foot. The curriculum must also include extensive water training; expeditionary troops must be strong swimmers and not view water as a barrier to movement.
In conclusion, recognizing the three distinct styles of modern warfare benefits the Army more than trying to make everything “[generic] Expeditionary.” Each style can teach the others their special tricks: COIN forces can innovate small-unit tactics and counter-infiltration methods, Expeditionary forces can teach marksmanship and other classical light infantry skills, Continental formations can bring everything together and improve everybody’s logistical options, and SOF can make items lightweight and highly efficient. It also benefits strategists, as their instruments will force them to think in terms of a COIN/Continental/Expeditionary triage, and act as a realist check on the optimism of leaders who would otherwise see the military as the answer to every problem. For a small amount of shuffling equipment and manpower, we can broaden our mental and doctrinal worldview, improve our position in the world, and become truly ready for any contingency.
[i] The only change that could be argued as a game-changer are drones, but these have numerous conventional countermeasures.
[ii] Strategic ends define the style of warfare, and tactics flow from these. Dividing styles by their tactics is misleading, as any tactic can serve a multitude of strategic goals
[iii] A modern Brigade is a WWII-era Regimental Combat Team with its own organic support, rather than relying on its parent division.
[iv] Much of urban combat closely resembles WWI-style Trench Warfare, and so the two do not need to be listed separately
[v] After President Diem’s assassination, General Westmoreland became its strongest proponent and continued to ask permission to launch it until his replacement by General Abrams.
[vi] There was some smuggling of heavy weaponry through Cambodian ports, but this was disrupted early in the war.
[vii] The French had 11,000 men to the Viet Minh’s 50,000. Four American divisions would number roughly 40,000 men, far larger than the French. It is also much bigger than the 6,000 Marines who fought at Khe Sanh.
[viii] They would possess the majority of the Army’s amphibious and supply ships
[ix] Mountaineer brigades/divisions would train to fight at elevations above 8,000 feet.
[x] Coincidentally this, too, was 6 divisions strong, although it would later grow into a continental army.