What’s better to use in combat: Unit replacement or individual troop rotation?

Best Defense is in summer reruns. Here is an item that originally ran on January 26, 2016.

By Cmd. Sgt. Maj. Robert Rush, Ph.D., U.S. Army (Ret.)
Best Defense chief of personnel policy

Straight answer? Neither.

In other words, there is no perfect or timeless replacement or manning system. Rather, there are only systems that best match the circumstances of the given time.

So: Unit rotation has worked best when casualties were low and combat episodic, or when an ample rotational base existed for a strategically static situation. But: Individual replacement has worked best when combat was sustained and fluid with high casualties of an unpredictable distribution.

Unit rotation improves cohesion and training standards to a point, but is resource intensive, difficult to mesh with other personnel policies, and introduces periods wherein everyone in a unit is new to the local situation at the same time. Initially we believed that if circumstances continued to feature low casualties and episodic combat, and the rotational demands downsized before units began multiple tours, then unit manning would do well. These past thirteen years, we had to stand the Army on its head to manage to rotate about 150,000 soldiers, a scale of movement undertaken during Korea and the Vietnam War up through the late ’80s as a matter of routine.

The US Army unsuccessfully attempted unit rotation with battle groups, battalions, brigades, and divisions at different times from the 1950s through the 1980s. After analysis, on all cases senior commanders preferred individual rotation to unit rotation because unit rotation proved to be more costly in terms of manpower, money and reduced readiness. Up until 2001, historically, whenever the Army entered into combat all attempts at unit rotation halted, with commanders relying on individual replacement to keep units filled while in the combat theater. There were never enough units to do otherwise and, probably more importantly, replacing veteran formations with those still green to combat or unfamiliar with local circumstances resulted in higher casualties in the near term as new units learned combat lessons the hard way.

Unfortunately, our extraordinary investment in time and resources to make unit manning work has been much less effective in prosecuting the wars in Afghanistan and Iraq, instead of deploying well trained units with a strong ethos and then keeping them in country for three years through individual rotation. As we know, with every rotation there is an acclimatization and “training wheels” phase for each newly arriving unit. One tenet of COIN, and for any type operations is to know the populace, and one year tours though essentially only ten months did not give organizations or the community they were supporting the time to get to know one another. It leaves and another unit would come in and begin the learning phase all over again. Unlike Vietnam, these really were one-year wars. Additionally, there is a triage effect on unit readiness for the Army as a whole as units’ cycle from preparing to deploy through deployed to just returned from deployment.

So how would the Army go about instituting a three-year unit stabilization in country while using individual rotation? (I see three years as the limit for a unit that is well-trained, cohesive and with a strong ethos can remain deployed.)

The initial cohort of soldiers departs between the nine and fifteen month period, with the leadership spaced out over time (those serving the additional three months given credit for those months). This would give an average of 21 months in country for each three person command team. As I see it, it’s like a family, you know your father from personal experience and your grandfather principally through the eyes of your father who had personal experience, but you don’t have a direct connection with your great grandfather. That and it is much easier to integrate individual soldiers into small units than it is multiple soldiers at the same time.

This in no way denigrates the value of unit cohesion. I have served in enough ranger, light and mechanized small infantry units to know that soldiers work better with someone they know. Nevertheless, I also believe that long-term association is no panacea, as soldiers do not need to live together over long periods to develop cohesion. Without good leadership, dynamic training, and dedication to the task at hand, the cohesion we seek can go bad — with defining moments frequently unreported undesirable or illegal events or activities as have occurred during OEF and OIF. My point is that good, stressful training, as well as a near full strength squad, is of more importance than entire groups of soldiers remaining together for long periods.

Command Sergeant Major Robert S. Rush, Ph.D., U.S. Army (Ret.), is author of Hell in Hürtgen Forest: the Ordeal and Triumph of an American Infantry Regiment, and GI: US Infantryman in World War II.

Photo credit: NASA/Flickr