war makes vacancies
Tocqueville on "Why Democratic Nations Naturally Desire Peace, and Democratic Armies, War":
In democratic armies the desire of advancement is almost universal: it is ardent, tenacious, perpetual; it is strengthened by all other desires and extinguished only with life itself. But it is easy to see that, of all armies in the world, those in which advancement must be slowest in time of peace are the armies of democratic countries. As the number of commissions is naturally limited while the number of competitors is almost unlimited, and as the strict law of equality is over all alike, none can make rapid progress; many can make no progress at all. Thus the desire of advancement is greater and the opportunities of advancement fewer there than elsewhere. All the ambitious spirits of a democratic army are consequently ardently desirous of war, because war makes vacancies and warrants the violation of that law of seniority which is the sole privilege natural to democracy.