The compulsion which we must use towards our enemy will be regulated by the proportions of our own and his political demands. In so far as these are mutually known they will give the measure of the mutual efforts; but they are not always quite so evident, and this may be a first ground of a difference in the means adopted by each.
The situation and relations of the states are not like each other; this may become a second cause.
The strength of will, the character and capabilities of the governments are as little like; this is a third cause.
These three elements cause an uncertainty in the calculation of the amount of resistance to be expected, consequently an uncertainty as to the amount of means to be applied and the object to be chosen.
As in war the want of sufficient exertion may result not only in failure but in positive harm, therefore, the two sides respectively seek to outstrip each other, which produces a reciprocal action.
This might lead to the utmost extremity of exertion, if it was possible to define such a point. But then regard for the amount of the political demands would be lost, the means would lose all relation to the end, and in most cases this aim at an extreme effort would be wrecked by the opposing weight of forces within itself.