History is filled with examples of powers which have fallen by neglect of these principles. "A state begins to decline when it permits the immoderate aggrandizement of a rival, and a secondary power may become the arbiter of nations if it throw its weight into the balance at the proper time."
In a military view, it seems plain that the sudden appearance of a new and large army as a third party in a well-contested war must be decisive. Much will depend upon its geographical position in reference to the armies already in the field. For example, in the winter of 1807 Napoleon crossed the Vistula and ventured to the walls of Königsberg, leaving Austria on his rear and having Russia in front. If Austria had launched an army of one hundred thousand men from Bohemia upon the Oder, it is probable that the power of Napoleon would have been ended; there is every reason to think that his army could not have regained the Rhine. Austria preferred to wait till she could raise four hundred thousand men. Two years afterward, with this force she took the field, and was beaten; while one hundred thousand men well employed at the proper time would have decided the fate of Europe.
There are several kinds of war resulting from these two different interventions:—
- Where the intervention is merely auxiliary, and with a force specified by former treaties.
- Where the intervention is to uphold a feeble neighbor by defending his territory, thus shifting the scene of war to other soil.
- A state interferes as a principal party when near the theater of war,—which supposes the case of a coalition of several powers against one.
- A state interferes either in a struggle already in progress, or interferes before the declaration of war.