Carl von Clausewitz developed the Schwerpunkt most likely under the impression of the twin battle of Jena and Auerstädt in 1806. If only the Prussian army had been able to unite its two main forces on one of the two locations, it could have defeated the French piecemeal instead of being defeated in parallel.
|Carl von Clausewitz|
His conclusion was the theoretical idea of a Schwerpunkt; focus on what counts, and draw as much strength away from lesser tasks as possible. You don't want to have the smaller battalions in a decisive battle.
The bigger battalions don't always win (empirical military history research yielded this counter-intuitive result), but they do so ceteris paribus (=if all else is equal).
To mass more troops for an important (THE important) battle is one way of how to acquire an unfair advantage prior to the decisive fight.
He called his concept "Schwerpunkt" based on a totally faulty understanding of Newtonian physics (he believed Schwerpunkt is where the most mass is concentrated), but he's not alone with confusion about terminology. The U.S. ground forces distorted Clausewitz' concept of a military Schwerpunkt beyond recognition.
Too much intro? Bad news, there's a second intro following:
Unlike some people's misguided beliefs, war does not mean that ethics can go overboard, hostile humans lives become worthless or that maximum destruction is an objective or at least desirable.
War means that you attempt to force your way to an acceptable outcome - and you do so with violence.
Violence that does not improve the outcome has no purpose. Such violence - death, mutilation and destruction - is as much unjustified as it would be during peacetime, applied to your own people. Some of this unjustified violence is unavoidable because you often cannot judge in advance its effects correctly, of course.
(Remark: The point of having military theory and doctrine is not just to reach a politically acceptable outcome in war; it's also about trying to keep the costs low!)
Good news; intros are over, now the real message:
Now what kind of violence in warfare is pushing for a desirable outcome and what's just dumb violence?
This is where the Schwerpunkt concept proves to be incredibly handy: Just apply it. Armies teaching and applying the original Schwerpunkt concept tend to end up with battle plans and decisions that have a Schwerpunkt (at most two; practical application is a bitch). Nothing that doesn't improve the odds of success at a Schwerpunkt is really improving the general outcome. A minor battle (let's say it's bloody to make it feel easier to follow the thought) - a bloody minor battle that doesn't influence the outcome at a Schwerpunkt is likely just unjustified violence.
An example (mentioned in an earlier post): Harassing fires are being despised by front-line troops rightly. Harassing fires rarely have important effects, but they make the whole mess even messier.
On the other hand; yours truly is a proponent of operational skirmishing. Wouldn't all such skirmishing be unjustified violence, far away from a Schwerpunkt?
Well, the Schwerpunkt concept evolved over time even in Germany. A Schwerpunkt does not need to be a small area on a map. It could even be a variable.
For example, a U.S. 8th Air Force bombing campaign Schwerpunkt during May 1944 and later was the destruction of German synthetic fuel production. They were not totally true to this (did many other attacks and spent much more resources than necessary), but for a while they kept their focus on it. The Schwerpunkt was no single battle location, but a critical economic activity.
Skirmishes could indeed be the Schwerpunkt themselves. Skirmishing would only be wasteful and unjustified violence if it's so poorly employed that it's got no operationally relevant effect.
One way how to improve the world is to make sure more officers understand that violence in itself does not necessarily serve a purpose (even if it entails no friendly casualties), that they can make wars less messy by judging the relevance of possible violent acts and to consider this as input in their decision-making.
Military history is quite rich with examples of bloody battles that were utterly unnecessary and politically irrelevant. Such tragedies are usually best-documented when they're most appalling, such as when they happen immediately before or even after cease-fires and peace treaties.
Military theory is not exactly strong in regard to omitting possible violence. Doctrines are more focused on how to make violence effective on a tactical level. Peacetime doctrine is even weak on economising on supply expenditure and personnel exhaustion (through stress and sleep deprivation).
There's still a lot of work ahead.