Precisely as it is the purpose of a besieging army to starve a particular city or territory into submission, so it is the aim of a blockading fleet to enforce the same treatment on the nation as a whole.
It is also essential to keep in mind that the question of contraband has nothing to do with a blockade, for, under this drastic method of making warfare, everything is contraband.

Contraband is a term applied to cargoes, such as rifles, machine guns, and the like, which are needed in the prosecution of war.
That a belligerent nation has the right to intercept such munitions on the way to its enemy has been admitted for centuries.

Differences of opinion have raged only as to the extent to which this right could be carried--the particular articles, that is, that constituted contraband, and the methods adopted in exercising it.

But the important point to be kept in mind is that where there is a blockade, there is no contraband list--for everything automatically becomes contraband.

The seizure of contraband on the high seas is a war measure which is availed of only in cases in which the blockade has not been established.
Great Britain, when she declared war on Germany, did not follow President Lincoln's example and lay the whole of the German coast under interdict.