The shutting up of a place by troops or ships, with the purpose of preventing ingress or egress, or the reception of supplies; as, the blockade of the ports of an enemy. Note: Blockade is now usually applied to an investment with ships or vessels, while siege is used of an investment by land forces. To constitute a blockade, the investing power must be able to apply its force to every point of practicable access, so as to render it dangerous to attempt to enter; and there is no blockade of that port where its force can not be brought to bear.