America’s Atomic Army of the 1950’s and the Pentomic Division

Written By: Lieutenant Colonel Lee Kichen, USA-Ret.

President, Dwight D. Eisenhower was a staunch fiscal conservative whose “New Look” defense policy relied heavily on nuclear weapons to be delivered by the Air Force and Navy, leaving relatively little in the defense budget for the Army. (National Archives)

Throughout the twentieth century, the Army was in a state of constant transformation and reform driven by changing missions and technological advances. The development of nuclear weapons at the end of World War II resulted in it becoming virtually irrelevant in the 1950s.

General of the Army Dwight D. Eisenhower, running for President in 1952, promised to end the Korean War, which had devolved into a bloody stalemate. Korea was a wake-up call for the unprepared Army that fought against North Korean and Communist Chinese forces with World War II weapons and tactics. The Army’s strategic vision lacked clarity, mistakenly assuming the next war would be like the previous wars, with time to mobilize and deploy from the continental United States.

The aftermath of the Korean War and changing national security policy required the Army to consider the nature of future wars, doctrine, weapons, and how to organize for both conventional and nuclear conflicts. Eisenhower’s predecessor, President Harry S. Truman, mistakenly assumed that America’s possession of atomic bombs would offset the Soviet Union’s quantitative advantage in conventional forces. The Soviet Union’s detonation of a nuclear device in late August 1949 dramatically ended America’s monopoly on nuclear weapons. Truman, wanting to avoid a direct confrontation with the Soviet Union and Communist China, adopted the foreign policy strategy of containment.

Eisenhower, by the end of 1953, his first year as President, made strategic nuclear weapons the foundation of his national security strategy. A fiscal conservative, he believed that defense and economic policies were inextricably linked. Republicans deemed excessive defense spending as self-defeating by threatening to bankrupt the economy, thus resulting in less military spending. Seeking a greater “bang for the buck” which would contain the Soviet Union at the least cost, Eisenhower turned to strategic nuclear weapons he considered more capable and cost-effective than conventional forces. By 1955, Eisenhower’s national security strategy put his former service on the road to becoming an atomic Army.

Eisenhower believed that nuclear weapons rendered the seizing and holding of territory irrelevant. His “New Look” policy of threatening “massive retaliation” with nuclear weapons was expected to render the Soviets incapable of fighting either a nuclear or conventional war and would allow America to reduce its costly conventional forces. The Air Force, with its ability to strike targets with nuclear weapons anywhere in the world, gained the largest share of defense dollars. The Army was the bill-payer for the New Look. Between 1953 and 1961, the Army’s budget declined from $16 billion to $9.3 billion, and the number of Regular Army divisions decreased from twenty to fourteen.

While the Air Force’s importance grew, Eisenhower viewed his former service as unimportant in defense planning for an atomic war. Secretary of Defense Charles E. Wilson and the Joint Chiefs of Staff provided scant planning guidance to the Army other than to reduce its budget and manpower. According to James C. Hagerty, Eisenhower’s press secretary, the Army’s atomic age roles were to occupy the enemy’s homeland after it was shattered by a nuclear strike or serve as a homeland security force if the Soviet Union struck the United States with nuclear weapons. The marginalized Army was ostensibly alone to revise its doctrine, acquire weapons and materiel, and organize how it would fight on a conventional and/or nuclear battlefield.

Army Chief of Staff General Matthew B. Ridgway disagreed with President Eisenhower over his defense policies and challenged the President’s position that “massive retaliation” with strategic nuclear arms was the primary deterrent to aggression. (National Archives)

The New Look precipitated a philosophical clash between two giants of World War II. General Matthew B. Ridgway, the Army’s Chief of Staff, challenged President Eisenhower’s position that “massive retaliatory power” was the primary deterrent to aggression.

In Ridgway’s view, the employment of nuclear weapons was not inevitable and might not be decisive. Furthermore, if used indiscriminately, their destructive power might dissuade both the United States and the Soviet Union from using them. Rather than relying on nuclear weapons, he argued for an adequately resourced and balanced ready force, contending that it would better deter a general war.

Ridgway argued that the Army was unprepared for future warfare, be it general or limited, atomic or non-atomic, leaving the nation with the dilemma of choosing to surrender or committing suicide.

Ridgway, although an opponent of massive retaliation with nuclear weapons, steadfastly believed tactical nuclear weapons would be necessary in future small-unit combat in jungles and other remote areas, and in large-scale combat in places such as heavily populated and urbanized Europe. Eisenhower and Wilson, however, publicly ignored Ridgway and in private questioned his intelligence. The animus between Eisenhower and Ridgway ran deep. At the conclusion of a meeting on 22 December 1954, with Secretary of Defense Wilson and the Joint Chiefs of Staff, Eisenhower reaffirmed his commitment to massive retaliation, emphasizing the finality of his decision. He concluded the meeting by remarking, “…as Commander in Chief [he] is entitled to the loyal support of [his] subordinates of the official position [he] has adopted and [he] expects to have it.” Eisenhower, in essence, fired Ridgway by not nominating him for a second two-year term as Chief of Staff.

General Maxwell D. Taylor (center), Ridgway’s successor as Chief of Staff, was no less strident than Ridgway in opposition to the New Look.

General Maxwell D. Taylor, Ridgway’s successor as Chief of Staff, was no less strident in his opposition to the New Look than Ridgway. He decried the lack of resources that the Army needed to fight a limited war.

In his view, a national security policy over-reliant on strategic airpower caused undue manpower reductions and exacerbated the lack of strategic and tactical airlift necessary for the Army to rapidly deploy, fight, and sustain conventional warfare.

Lieutenant General James M. Gavin, the Army’s Deputy Chief of Staff for Research and Development under Ridgway and Taylor, believed that strategic nuclear weapons “served no sane purpose.” (National Archives)

Lieutenant General James M. Gavin, Deputy Chief of Staff for Research and Development, judged that strategic nuclear weapons “served no sane purpose” other than possibly causing hundreds of millions of deaths, many of whom would be in allied or neutral countries. Chairman of the Joint Chiefs of Staff Admiral Arthur W. Radford, supporting President Eisenhower, reminded the service chiefs that for planning purposes nuclear weapons would be employed at the outset of hostilities and that they would be available for limited conflicts as well as general wars.

The Army continued its objections to the New Look. During Eisenhower’s administration, the Army was stuck in second place; many officers wondered if the President had decided that the Army was “merely desirable.”

Major General Gerald J. Higgins told Ridgway he was retiring because “I am convinced that if the present trends continue, the Army will soon become a service support agency for the other armed services. Army General Staff officers leaked classified studies detailing the Army’s objections to the New Look strategy. One study leaked during the so-called “Colonels’ Revolt” asserted that the “U.S. was grossly unprepared to meet the communist threat…[that] the administration…violated the first principle of strategy…by failing to shape our military strength to meet likely dangers.” This study decried the continuous pouring of manpower and money into an Air Force, which was by then markedly neutralized by the Soviet Union’s growing nuclear arsenal.

This chart shows the organization of the Pentomic division. All airborne and infantry divisions were reorganized as Pentomic divisions, while armored divisions maintained their previous organization established during World War II. (Taken from Maneuver and Firepower: The Evolution of Divisions And Separate Brigades).

Despite the Army’s senior leadership objections to the New Look, it began to accept the atomic revolution. The Army accepted the reality that by embracing tactical nuclear weapons and reorganizing itself into a hybrid atomic/non-atomic force, it could regain a semblance of its former relevance.

As a result, throughout the 1950s, the Army pursued evolving missile technology in three areas: space exploration; tactical surface-to-surface; and air defense. Before Ridgway retired, he directed the Army War College to initiate a study entitled “Doctrinal and Organizational Concepts for the Atomic-Nonatomic Army during the Period 1960-1970,” which had the short title of PENTANA. Taylor inherited the findings of the study, completed in December 1955, recommending a totally air-transportable 8,600-man division able to fight as a conventional or nuclear force to replace the existing infantry, airborne, and armored divisions.

Many theorists considered a unit’s ability to quickly disperse on a nuclear battlefield critical to its survivability. The regiments employed in World War II and Korean War-era divisions lacked the capability to rapidly disperse. They were too unwieldy and dependent on support from other divisional units to preserve their combat effectiveness. When augmented with engineers, artillery, communications, and enhanced logistics capacity, the regiment acquired the ability to fight as an independent formation. However, experience suggested that heavily reinforced regiments lacked the quickness and agility needed on a nuclear battlefield. The large regimental combat team would present a large, lucrative target for a nuclear-capable enemy; the loss of a regiment would reduce the division’s combat power by a third. For dispersion to work, Lieutenant General Gavin felt that on an atomic battlefield, a unit should be like an amorphous biological cell, an island that would be hard for an enemy to detect and destroy. He claimed that “Severe damage to one part of a division composed of cellular components would not preclude the rest [of the division] from fighting on.”

Troopers of 2d Battalion, 187th Airborne Infantry Regiment, 101st Airborne Division, ride in an H-34 helicopter during early Pentomic training at Fort Bragg, North Carolina, 27 January 1957. (National Archives)

Gavin and others maintained that a reorganized battalion should be large enough to fight independently, yet small enough to be expendable. With the battalion eventually becoming the building block of the new division, the Army eliminated the regiment and its battalions and organized “battle groups,” each commanded by a colonel.

The Army intended that battle group organization would be more sustainable to greater combat power than the regimental combat team. The battle group consisted of five infantry companies each with five platoons; the group’s combat support company had a radar section, a heavy mortar platoon, a reconnaissance platoon, and an assault weapons platoon. In 1961, the Pentomic Divisions received the M28/29 Davy Crockett recoilless gun which fired a .01 kiloton nuclear round capable of emitting sufficient radiation to kill everyone within 500 meters of the detonation point.

In addition to nuclear-capable 155mm and 8-inch howitzers, the Pentomic division’s nuclear punch could be delivered by the Honest John rocket.

The group’s headquarters and service company provided it with signal, maintenance, and medical support. Habitually attached to the battle group was a 105mm howitzer battery.

The Army expected that division commanders, with a greater number of units available, would have more options in deploying their formations in depth or arraying them to fight in all directions on a non-linear nuclear battlefield.

The division artillery’s composite battalion included Honest John rockets, along with 155mm and 8-inch howitzers, all of which could employ conventional, nuclear, and chemical rounds. The Honest John, however, presented several problems; as a free-flight rocket, it was inaccurate, too heavy to be air-transportable, and, consisting of three separate components, it had to be assembled on the battlefield in a process that took a considerable amount of time.

Soldiers hold cased guidons of the 3d Infantry Regiment during the changeover to the 1st.

The division base included a reconnaissance squadron, an engineer battalion with five companies, a signal battalion, and an aviation company. The division trains consisted of ordnance, transportation, and medical battalions, along with administrative and quartermaster companies.

Rounding out the division base was a medium tank battalion with five companies, each equipped with M48 tanks armed with a 90mm main gun. Tests proved the employment of armor was problematic. Although doctrine held that tanks were the best vehicles to exploit the immediate effects of nuclear weapons and should move with the division’s nuclear-capable systems, the earliest variant of the M48 lacked an integrated nuclear, biological, chemical protection system, which made the tank largely ineffective during nuclear operations.

A 106mm recoilless rifle gun crew from 1st Battle Group, 12th Infantry, 4th Infantry Division, sets up a position during training at Camp Desert Rock, Nevada, 8 August 1957. The training exercise was held in conjunction with the Army’s 1957 atomic testing nearby.

Taylor dubbed this formation the “Pentomic” division by highlighting the number of five battle groups, companies, platoons, and supporting units, as well as the division’s atomic capability. Some critics called this label an atomic age marketing tool. Although the Army intended to convert all divisions to a Pentomic configuration, the armored division largely retained its previous organization as its subordinate combat commands demonstrated in World War II the same flexibility deemed essential to the Pentomic division.

The Army’s three airborne divisions (11th, 82d, and 101st), beginning with the 101st Airborne Division in the fall of 1956, were the first to transition to the Pentomic organization; by June 1958, all of the Army’s infantry divisions had been reorganized as Pentomic formations. The Pentomic division’s rhythm was intended to be a constant cycle of dispersion, convergence massing, penetration, and exploitation by the battle groups. Dispersing battle groups in the defense was envisioned to lessen the effects of a nuclear attack on the division and, while still dispersed, the battle groups would employ immediate nuclear counter-strikes to isolate the battle area, destroy enemy nuclear weapons, and interrupt and defeat ground and air attacks.

Soldiers from Company E, 1st Airborne Battle Group, 187th Infantry, man a checkpoint near Beirut Lebanon, during Operation BLUE BAT, 4 August.

The flanking maneuver once described as the pinnacle of offensive operations became doctrinally superfluous. Penetration became the primary scheme of maneuver during offensive operations. Instead of pounding away at enemy defenses with conventional, frontal attacks needlessly attritting combat power, nuclear fires would create gaps in the enemy defenses. Massed battle groups fighting conventionally or with nuclear weapons would then move through the gaps to the enemy’s rear.

The width of the gap was an important consideration, as penetrating through an exceedingly narrow gap would delay the exploitation phase. The longer the penetration force was in a column formation, its combat power would decrease exponentially. Units concentrated in narrow gaps presented lucrative targets for enemy conventional or nuclear fires.

The Pentomic division’s mantra of dispersion, flexibility, and mobility, however, rang hollow. With the national security strategy based on expensive nuclear weapons, along with fighter and bomber aircraft, there were scant resources for the Army to acquire enough modern tanks, infantry carriers, trucks, and long-range radios required to move more than one battle group at any one time. The dual capable nuclear-conventional division cost approximately thirty-five percent more than the older triangular division. Although the PENTANA study recommended a strength of 8,600 soldiers, the Pentomic division topped out at 13,738. The Pentomic division failed to achieve savings by substituting expensive missiles and nuclear fires for manpower. To preserve a semblance of conventional capability, planners increased the ratio of combat troops to combat support and service support soldiers which, paradoxically, reduced the division’s capacity to sustain its combat units. Still unable to sustain the division, commanders reversed themselves and resorted to stripping troops from combat units to augment combat service support units which were too understrength to support the division.

Two soldiers from Company B, 2d Battle Group, 6th Infantry, man an M60 machine gun during training in West Berlin, Federal Republic of Germany, 17 April 1963. By the end of 1963, the Army had ceased using the Pentomic.

It became increasingly apparent neither side would benefit from employing tactical nuclear weapons. The use of tactical nuclear weapons would not offset Communist manpower. Instead, tactical nuclear warfare producing inordinately high casualties would require larger rather than smaller armies.

The Army soon came to the realization that tactical nuclear war would devastate its European allies and likely lead to a full-scale nuclear exchange between East and West. Command of the division organized for optimum flexibility proved unwieldy; the large span of control was challenging for even the most talented general officer. Without intermediate command echelons such as a brigade or a regiment with its subordinate battalions, the division commander was required to concern himself with as many as sixteen subordinate units, violating the optimum span of control of three to five elements. Contrary to expectations, numerous field training exercises revealed that the battle group was not suitable for conventional operations despite growing expectations that the next war would be non-nuclear.

General Paul L. Freeman, Jr., (left), commander of U.S. Army Europe, greets General John P. McConnell (center), deputy commander of U.S. European Command, and Secretary of Defense Robert M. McNamara at Rhein-Mein Air Base, West Germany, 7 September 1962.

Army senior leaders bashed the Pentomic division. General Hamilton Howze cited the division’s “…ridiculous aspects…as too redolent of Hollywood or Madison Avenue.” Lieutenant General Donald V. Bennett dismissed the division as simply a “device to say ’Yes, the Army has moved into this nuclear age.’” He believed that the division’s deficiencies in mobility and logistics rendered it virtually ineffective. General Paul L. Freeman, Jr., opined, “Every time I think of the Pentomic Division, I thank God we never had to go to war with it.” General Taylor, the “father” of the Pentomic division, was largely responsible for its demise. By the time Eisenhower left office in January 1961, the New Look was considered too rigid, unimaginative, and lacking boldness.

President John F. Kennedy’s administration immediately scrapped Eisenhower’s massive retaliation national defense policy for “Flexible Response” first discussed by Taylor in his book The Uncertain Trumpet, written after he retired in 1959. Kennedy, who considered Taylor a brilliant and incisive officer, recalled him to active duty as his military advisor and later appointed him Chairman of the Joint Chiefs of Staff. President Kennedy, undoubtedly influenced by Taylor, declared the death of the Pentomic division when he directed Secretary of Defense Robert M. McNamara “…to undertake a reorganization and modernization of the Army’s divisional structure, to increase its non-nuclear firepower, to improve its tactical mobility in any environment to ensure its flexibility to meet any indirect or direct threat…” Over the next several years, the failed Pentomic division would be replaced by the Reorganization of Army Divisions (ROAD) structure, based around three maneuver brigades, and this would serve the Army in Vietnam and through the latter years of the Cold War.