January 16, 2008: After decades of effort by a determined group of officers, the army has finally accepted lessons learned during World War II. The most important lesson is that small units of troops must be kept together, and replacements for casualties integrated into the unit carefully. This has been done during the current war, and the capabilities of the combat units has been astounding. But many journalists and politicians are still unaware of how important this "cohesion" thing is.

Cohesion is nothing more than keeping small units of combat troops together long enough for them to bond, and become an effective team. Same things as with sports teams. But from the end of World War II, until the late 1990s, the "individual replacement" system was used, which constantly destroyed this cohesion. Combat losses were replaced on an individual basis. Same thing in peacetime. When a soldier leaves, usually at the end of his enlistment or tour of duty, a single replacement was brought in. This meant that units lost over five percent of their troops each month. Where this hurts was at the lowest level. An infantry fire team, of four or five troops, is only as effective as it is coordinated. Take one guy out and replace him with a new soldier, and it takes weeks, or months, for that team to get it's combat edge back. Same with a tank or artillery crew. Or even a team of clerks or mechanics.

The alternative was to form units, keep them together through training, then send them overseas, or hold them ready for an emergency, for about a year. While some troops are lost to normal attrition (illness, disciplinary problems, or combat casualties), the unit is largely intact. This approach has worked wonders on the battlefield. Troops know the people they are working with, and appreciate waiting until they are back home to incorporate new people. The battlefield is not the place to do that.

The U.S. Army has, for the last decade, been making more of an effort to send entire units overseas, instead of individual replacements. This is the "cohort system" and the army is extending its use from combat, to combat support units. It's not been an easy transition.

Now the army is using the cohort system for combat support units in non-combat assignments. Patriot anti-aircraft missile battalions are now rotated overseas as complete battalions. Formerly, individual batteries had been sent over, and these functioned more effectively than batteries that used individual replacements. It follows that the entire battalion will be more effective if all the troops are sent over at once. All the weapons and equipment for the battalion stay ioverseas, with just the troops moving.

What's amazing about this is that the problem was identified and analyzed at the end of World War II. Academics (who were often combat veterans) wrote papers about the phenomenon. But many senior generals didn't get it. It wasn't until after Vietnam, that the senior brass recognized the problem enough to start implementing a solution. Naturally, the "cohort" system costs more money, and in the Pentagon, there are many special interests looking for that money. For the moment, those special interests aren't grabbing some extra cash at the expense of stability and capabilities of the combat units.