Blockade

In international law. A marine investment or beleaguering of a town or harbor. A sort of circumvallation round a place by which all foreign connection and correspondence is, as far as human power can effect it, to be cut off.

1 C. Rob. Adm. 151.

It is not necessary, however, that the place should be invested by land, as well as by sea, in order to constitute a legal blockade; and, if a place be blockaded by sea only, it is no violation of belligerent rights for the neutral to carry on commerce with it by inland communications.

1 Kent, Comm. 147.

The actual investment of a port or place by a hostile force fully competent, under ordinary circumstances, to cut off all communication therewith, so arranged or disposed as to be able to apply its force to every point of practicable access or approach to the port or place so invested.

Bouvier.

It is called a "blockade de facto" when the usual notice of the blockade has not been given to the neutral powers by the government causing the investment, in consequence of which the blockading squadron has to warn off all approaching vessels.