U.S. Army Transformation: Division Units to Units of Action

The Cold War Origins: The Pentomic Concept

At the Pentagon, briefings routinely begin with the old adage that "the only thing constant today is change." Since the age of the Cold War, the United States Army has faced change at home and abroad, experiencing not only a massive transformation in technology and infrastructure, but also in its worldwide approach to warfare. As the era of front-line battles gave way to urban streets and insurgency, the Army transitioned its structural paradigm to mirror rapidly shifting needs, abandoning the Three Brigade Division Units in favor of Units of Action.

This organizational shift had roots in Capitol Hill politics and internal dissent within the Pentagon, but it was a desperately needed restructuring to meet the demands presented by the Iraq War — demands vastly different from those experienced during the Cold War. In the early 1950s, Soviet forces overwhelmed many Western nations, and U.S. Army planners decided that if American ground forces were to gain strength in the future, they would have to exhibit superior mobility and increased firepower.

That firepower would come from atomic weapons, which provided superior tactical and logistical mobility capable of defeating an army that was numerically greater. This new strategy, which began in early 1953 and 1954, brought the first delivery of atomic weapons to Europe. Only two years later, in 1956, two infantry divisions were replaced by one airborne unit and one armored division. This first occurred when the 11th Airborne Division replaced the 5th Infantry Division in early 1956, followed by the replacement of the 4th Infantry Division in Frankfurt in May 1956 by the 3rd Armored Division.

Later that same year, the Department of the Army proposed a plan of reorganization adapting infantry, armored, and airborne divisions to atomic warfare. The new plan, called the Pentomic Concept, was approved for Army-wide implementation as designated in November by USEUCOM, which first allowed for the transformation of the Seventh Army divisions. The 11th Airborne was accordingly restructured into five major battle groups, all "completely air transportable," in line with the new organizational pattern.

Of the other four divisions in Europe, the 2nd Armored Division and the 10th Infantry achieved restructuring by July 1, 1957; the 8th Infantry Division by August 1; and the 3rd Armored Division by October 1 of the same year.

The new structure of the Pentomic Concept meant the loss of one 155-mm and two 105-mm battalions in the infantry division, though some units gained capability. The infantry division also lost a regimental tank company, but with more than 100 tanks remaining, the blow was cushioned; additionally, the reconnaissance company was replaced with an armored cavalry battalion. The primary beneficiary of the transformation was a single composite unit comprising one 8-inch howitzer, an Honest John rocket, and two 155-mm howitzer batteries, which significantly increased firepower capabilities. Additionally, six 90-mm antiaircraft artillery battalions switched to Nike missile systems, and USAREUR reorganized its Honest John batteries into well-maintained battalions.

The massive overhaul of the system achieved near success in concept. Ultimately, the restructuring meant that Pentomic units, capable of fighting a nuclear war, would also prove to be a formidable force in conventional battle.

The 1960s brought a changing political scene, shaped by tensions over Berlin and the emergence of Vietnam. As a result, the military was forced to proactively adapt to the shifting landscape of warfare. The fast-moving currents of international politics precluded a static concept of combat division, and the preemptive restructuring of the Pentomic system still demanded further attention. "Although the Pentomic divisions were effective combat units," military historian D.J. Hickman observed, "experience, as well as examination of the world situation and of military requirements, disclosed areas in which significant improvements could be made."

Flexible Response and the ROAD Reorganization

The refocusing lens provided by world events shed light on the improvements that could be made in American military organization. "By the early 1960s, world events focused attention on the fact that Army combat forces faced a wide range of possible situations."

Among these, the emerging strategy of "flexible response" was proving not only to be the most popular but also the most viable. If combat units were to be tailored to meet the demands of specific situations, their tactical mobility and firepower would have to match the environment, enemy, and shifting technological landscape. As discussion gave way to action, the Reorganization Objective Army Divisions (ROAD) strategy was designed, allowing for specific and varied strategic requirements.

Despite ongoing efforts to develop American nuclear capability, the new emphasis on the requirements of limited wars proved wise. The Seventh Army divisions were reorganized under ROAD in 1963, after extensive preparation to reequip them with stronger technology. The ROAD concept required the complete mechanization of combat units with major equipment, outlining a sweeping mechanized overhaul of the Seventh Army, which had been equipped with the M48 tank, M59 armored personnel carrier, and M74 and M51 tank recovery vehicles. While many of these machines remained functionally useful, they had been developed during or before the Korean War and were technologically dated for modern battle.

The new equipment began arriving two years before USAREUR was able to fully incorporate it. In September 1961, Seventh Army units received their first shipments of the M-14 rifle, replacing the M-1, the carbine, the Browning automatic rifle, and the Thompson submachine gun.

The addition of the M60 battle tank and the M113 armored personnel carrier supplanted their earlier prototypes; they were faster, lighter, and, where necessary, more accurate. A shoulder-fired M70 grenade launcher provided a medium-range capability not covered by the maximum-range hand grenade or the short-range mortar. Units were outfitted in ways that further protected soldiers and presented a more formidable force in battle; previously identified capability gaps were addressed, and the Army brought its units up to modern standards, even adding a nuclear-capable Davy Crockett.

During 1962, new supplements continued to arrive in Europe and undergo extensive testing. USAREUR troops subjected the new machinery to rigorous scrutiny and added to their ranks the French-designed Entac anti-tank missile, Iroquois helicopters, and Mohawk aircraft. In 1963, the physical aspects of the ROAD divisions were complete, and conversion began. USAREUR was required to complete this process seamlessly so as not to jeopardize combat readiness; as a result, most machinery was not only on hand but largely already issued.

The total conversion, which began in February, was completed in 30 days, marking a new era for Army structure, a timely standard for expedience, and a burgeoning epoch of highly technical battle.

The ROAD organization provided USAREUR with a modern and flexible framework for equipping its forces. Each new division now consisted of a base and a varying mixture of combat maneuver battalions — either tank, mechanized infantry, or airborne — while in Berlin, the straight infantry battalions saw their final days. The new bases contained all elements required by any division, including command, control, artillery, a support command, and three brigade headquarters. These units were identical in base structure, while their equipment, organization, and methods of operation could vary by mission. Likewise, all battalions had a basic structure organized and equipped to provide mobility, firepower, and combat capability across shifting environmental conditions.

The need for change was underscored by this massive transformation, which fundamentally altered the terrain of American-executed warfare. New mechanics blended with established needs to provide coherence to the military unit: the mechanized infantry battalion offered lightweight, armor-protected, cross-country mobility, while the airborne battalion was adaptable to a wide range of environments. The overall effect was a tactical mobility suited to European and other international environments that provided a near-match to Soviet capabilities, other adversaries, and NATO partners.

Division-86 and the Three Brigade Structure

By 1982, analysis of combat had crystallized inside the AirLand Battle concept and evolved into the Division-86 force structure. At this point, the Army still focused its efforts primarily on Europe, which both the government and the voting public viewed as key to national security. The emerging Division-86 structure focused on a standardized heavy division, combining armored and mechanized infantry divisions and making maximum use of new equipment.

The Division-86 proposal maintained much of the flexibility valued in the ROAD structure. The most significant change occurred within the new heavy division, which totaled approximately 20,000 officers and enlisted soldiers. The new structure's basic composition included one Headquarters and Headquarters Company and three Brigade Headquarters. Additionally, it mandated one Military Police Company, one Signal Battalion, one Air Defense Artillery Battalion, one Engineer Battalion, one Military Intelligence Battalion, one Reconnaissance Battalion, one Division Artillery, one Air Cavalry Brigade, and one Division Support Command, in addition to numerous maneuver elements.

With the Division-86 system change, the Army also published a Training and Doctrine Command guide to ensure successful implementation. On October 1, 1982, the Command published tables of organization and equipment to implement this second attempt at achieving the heavy division concept. The tables, which outlined both armored division and mechanized infantry configurations, set out five deployment variations. The different cases involved the assignment of either five or six armored and four or five mechanized infantry battalions to an armored division; additionally, each mechanized infantry division was equipped with both five armor and five mechanized infantry battalions.

Institutional variations also covered the integration of varying equipment, including M60 tanks, M113 armored personnel carriers, the new M1 Abrams tanks, and Bradley infantry fighting vehicles. These configurations of the basic concept would allow for heavy divisions ranging from 19,000 to 20,500 officers and enlisted men.

The published tables conformed largely to the originally proposed ideas with very few changes. In the actualized plan, cavalry vehicles replaced tanks in the reconnaissance squadron, which now consisted of two ground and air troops, leaving no motorcycles and making the squadron part of the aviation brigade. This development in organization was key to the nascent brigade structure, in which the finance unit was transferred to corps level. In a bow to modernization, the Army reorganized its intelligence battalion to field electronic warfare, surveillance, and service companies. Final changes included the return of the medical command; meanwhile, the target acquisition element was reduced to a battery and the chemical company was returned to divisional level.

To counter the Soviet Union's high density of artillery and improved weapons, Division-86 was also forced to increase its division artillery. To that end, it fielded three battalions of 155-mm self-propelled howitzers, organized into three batteries each having eight pieces. Additionally, each battalion included sixteen 8-inch howitzers, nine mounted multiple launch rocket systems, and a target acquisition battalion.

The new air cavalry attack brigade — the offspring of the 1st Cavalry Division and the 6th Cavalry Brigade at Fort Hood — provided its first anti-tank role in the division. The air cavalry brigade, which fielded 134 aircraft, consisted of two attack battalions each with four companies of six helicopters, a combat support aviation battalion, aircraft maintenance, and a reconnaissance squadron.

While the transformation proved difficult, the settling into the Three Brigade structure was a key moment in modern Army history. It was representative of the accommodation between entrenched institutional traditions and a brand-new system in constant flux. The Three Brigade structure allowed for dislocated connectivity as well as heavy machinery, all geared toward fighting a specific enemy.