Military theorists and strategists like Sun Tzu have viewed attrition warfare as something to be avoided. In the sense that attrition warfare represents an attempt to grind down an opponent through superior numbers, it represents the opposite of the usual principles of war, where one attempts to achieve decisive victories through maneuver, concentration of force, surprise, and the like.
On the other hand, a side which perceives itself to be at a marked disadvantage in maneuver warfare or unit tactics may deliberately seek out attrition warfare to neutralize its opponent's advantages. If the sides are nearly evenly matched, the outcome of a war of attrition is likely to be a Pyrrhic victory.
The difference between war of attrition and other forms of war is somewhat artificial, since war always contains an element of attrition. However, one can be said to pursue a strategy of attrition when one makes it the main goal to cause gradual attrition to the opponent, or when one considers high losses of men or resources as acceptable so long as the enemy suffers equally high loss, as opposed to trying to conquer terrain or to isolate large sections of the enemy through maneuver, or trying primarily to preserve ones own forces.
Historically, attritional methods are tried when other methods have failed or are obviously not feasible. Typically, when attritional methods have worn down the enemy sufficiently to make other methods feasible, attritional methods are abandoned in favor of other strategies.
Attritional methods are in themselves usually sufficient to cause a nation to give up a non-vital ambition, but other methods are generally necessary to achieve unconditional surrender.
It is often argued that the best-known example of attrition warfare was during World War I on the Western Front. Both military forces found themselves in static defensive positions in trenches running from Switzerland to the English Channel.
For years, without any opportunity for maneuvers, the only way the commanders thought they could defeat the enemy was to repeatedly attack head on, to grind the other down.
Attritional warfare in World War I has been shown by historians such as Hew Strachan to have been used as a subsequent excuse for failed offensives. Erich von Falkenhayn later claimed that his tactics at Verdun were designed not to take the city, but rather to destroy the French Army in its defense.
In practice the German Offensive was intended to go as far as possible and had no obvious design to minimize German casualties and maximize French casualties. Attrition was therefore used later in the battle to shift the focus away from Falkenhayn's tactical failure, rather than a goal of the battle itself.
Attrition to the enemy was easy to assert and difficult to refute, and thus may have been a convenient face-saving exercise in the wake of many indecisive battles. It is in many cases hard to see the logic of warfare by attrition because of the obvious uncertainty of the level of damage to the enemy, and of the damage that the attacking force may sustain to its own limited and expensive resources, while trying to achieve that damage.
That is not to say that a general will not be prepared to sustain high casualties while trying to reach an objective. An example in which one side used attrition warfare to neutralize the other side's advantage in maneuverability and unit tactics occurred during the latter part of the American Civil War, where Ulysses S. Grant pushed the Confederate Army continually, in spite of losses, confident that the Union's supplies and manpower would overwhelm the Confederacy even if the casualty ratio was unfavorable, which indeed proved to be the case.