A paper to be included in a volume devoted to the comparison to the comparative history of blockages, edited by Professor Jean-David Avenal. INTRODUCTION Blockade, as a formal and systematic weapon in modern naval warfare, distinct from battle and maneuver, developed during the Napoleonic wars and was further refined by the Royal Navy in its decades-long campaign after 1815 to suppress the African slave trade (1). In spite of this extensive history, it was not until the Treaty of Paris ending the Crimean War that a Declaration Respecting Maritime Law, dated April 16, 1856, formally established the general principles of international law that would define blockade and abolish privateering, blockade's traditional response. Blockades were described in four short articles...