The Long Fight: Replenishing Manpower in a War Without End

Wars of limited duration can be fought on the basis of immediate reserves and patriotic surges. Wars without a clear end date—such as Ukraine’s defence against Russian aggression—demand something far harder: a sustainable system for replenishing manpower over years, perhaps decades, without breaking the army, the economy, or the nation’s spirit.

Ukraine has now been engaged in full-scale war for more than three years. Her front-line troops are battle-hardened but often exhausted. The need to rotate units, integrate new recruits, and maintain combat effectiveness is relentless. The question is no longer only how to win battles, but how to maintain the human foundation of the armed forces for as long as the conflict demands.

The Nature of the Manpower Challenge

The Ukrainian Armed Forces face a triad of pressures:

1. Attrition – Casualties from combat, injury, and illness steadily reduce effective numbers. Even with battlefield medicine and rapid evacuation, the losses mount.

   
   

2. Exhaustion – Soldiers in high-intensity sectors cannot remain indefinitely at the front. Rotation is vital, but rotation requires fresh units to take their place.

   
   

3. Demographics – Ukraine’s working-age population has been reduced by displacement, emigration, and the departure of millions of women and children abroad. This shrinks the pool from which new recruits can be drawn.

In a long war, the problem is cumulative. Each year without decisive victory increases the strain, making manpower a strategic resource as important as ammunition or fuel.

Lessons from History

The manpower challenge is not unique to Ukraine. The First World War saw European armies implement rolling conscription systems, recalling older soldiers for rear duties to free younger men for the front. Israel, facing constant threat, has long maintained a model of universal conscription with periodic reserve mobilisation, designed to refresh its military without hollowing out the economy.

The Soviet Union in Afghanistan and the United States in Vietnam faced a different dynamic: political limits on mobilising reserves led to troop fatigue, morale collapse, and public opposition. The lesson is clear—without a fair, transparent, and sustainable system, manpower shortages become political crises.

Ukraine’s Current Approach

Ukraine has progressively tightened mobilisation laws since 2022. Initial waves relied heavily on volunteers, reservists, and those with prior service. More recent measures have lowered mobilisation ages and extended obligations for those already serving.

The government has also begun to expand specialist recruitment—targeting engineers, drone operators, medics, and artillery specialists—acknowledging that modern war demands skill as much as raw numbers. However, logistical and political challenges remain:

• Resistance to recalling older or medically borderline citizens.

  
  

• Balancing military needs with the imperative to keep key civilian sectors functioning.

  
  

• Ensuring that mobilisation is seen as equitable, avoiding resentment over perceived exemptions.

The Role of Rotation and Rest

A sustainable manpower policy must build structured rotation cycles. A soldier’s physical and psychological endurance has limits. Without predictable rest, even elite units degrade in performance.

Rotation requires surplus manpower—enough to rest one-third of combat units at any given time while still maintaining front-line strength. This, in turn, demands forward planning and the maintenance of training pipelines that can replace losses before they are felt at the front.

Alternative Manpower Sources

In a war of indefinite duration, Ukraine may need to diversify her manpower base:

1. Returning Citizens Abroad – Incentives, not just obligations, to encourage men of service age who left in 2022 to return.

   
   

2. Foreign Volunteers and Contracts – Formalised pathways for experienced veterans from allied countries to serve in Ukrainian units, with legal protections and clear command integration. Although the International Legion for the Defence of Ukraine was established to hire foreign recruits, implementation of this initiative has been mixed both in terms of the quality of recruits and the value of their deployment.

   
   

3. Expanded Role for Women – Many already serve in medical, communications, and logistics roles; expanding combat and command opportunities could significantly broaden the recruitment pool.

   
   

4. Civilian-Military Blends – Using trained reservists in rotational call-ups, serving short tours interspersed with civilian life, as in Nordic defence models.

The Psychological Dimension

Long wars wear not only on bodies but on will. Soldiers returning from intense fighting need proper reintegration, mental health support, and the knowledge that their service is part of a coherent national plan, not an endless cycle.

Failure to address the psychological impact risks hollowing out the future reserve pool—those who have served may be unwilling or unable to return without assurance of purpose and proper care. There is surely a cultural aspect to this - an aversion to psychiatry and psychological help - but efforts must be made to overcome this.

The Political Question

Mobilisation is a test of political leadership. The public will accept hardship if it believes it is shared fairly and that the war’s aims are clear. Any perception of corruption in exemptions, or of arbitrary treatment, will corrode support.

A transparent, rules-based system—explained in plain language, enforced without favour—is as vital as the actual numbers mobilised.

Manpower as a Strategic Weapon

In a war without end, manpower policy becomes grand strategy. It must integrate the military, economic and social spheres. Ukraine’s ability to rotate, rest, and replenish her forces will determine not just her ability to hold the line today, but her capacity to fight, adapt and prevail tomorrow.

If Ukraine can make this system work—fairly, efficiently and humanely—she will deny Russia one of her few real advantages: sheer demographic mass. In a long fight, it is not the size of the population that counts, but the ability to turn willing citizens into capable, sustained defenders of the state.