The truth is, that in all the larger achievements of sea power--those, that is, to which a combination of naval and military force is indispensable--it is impossible to disengage the influence of one of these factors on the final issue from that of the other, and perhaps idle to attempt do to so. They act, as it were, like a chemical combination, not like the resultant of two separate but correlated mechanical forces, and their joint effect may be just as different from what might be the effect of either acting separately as water is different from the oxygen and hydrogen of which it is composed. But their operation in this wise can only begin after the command of the sea has been secured, or at least has been so far established as to reduce to a negligible quantity the risk of conducting military operations across seas of which the command is still nominally in dispute. Now there are several phases or stages in the enterprise of securing the command of the sea; but they all depend on the power and the will to fight for it. There is no absolute command of the sea, except in the case of hostilities between two belligerents, separated by the sea, one of whom has no naval force at all. The solitary case in history of this situation is that of the War in South Africa. A similar situation would arise if one of two belligerents had completely destroyed all the effective naval force of the other. But that is a situation of which history affords few, if any, examples. Between these two extremes lies the whole history of naval warfare.