The other is resolution.
As the battle is the feature in War to which attention was originally chiefly directed, and as time and space are important elements in it, more particularly when cavalry with their rapid decisions were the chief arm, the idea of rapid and correct decision related in the first instance to the estimation of these two elements, and to denote the idea an expression was adopted which actually only points to a correct judgment by eye.

Many teachers of the Art of War then gave this limited signification as the definition of coup d'oeil.

But it is undeniable that all able decisions formed in the moment of action soon came to be understood by the expression, as, for instance, the hitting upon the right point of attack, &c.

It is, therefore, not only the physical, but more frequently the mental eye which is meant in coup d'oeil.

Naturally, the expression, like the thing, is always more in its place in the field of tactics: still, it must not be wanting in strategy, inasmuch as in it rapid decisions are often necessary.