Note 578 — Chapter IX · —Oceans And Enclosed Seas

At the beginning of the sixteenth century the Indian Ocean was a Portuguese sea. Spain was trying to monopolize the Caribbean and even the Pacific Ocean. But the immense areas of these pelagic fields of enterprise, and the rapid intrusion into them of other colonial powers soon rendered obsolete in practice the principle of the mare clausum, and introduced that of the mare liberum. The political theory of the freedom of the seas seems to have needed vigorous support even toward the end of the seventeenth century. At this time we find writers like Salmasius and Hugo Grotius invoking it to combat Portuguese monopoly of the Indian Ocean as a mare clausum. Grotius in a lengthy dissertation upholds the thesis that "Jure gentium quibusvis ad quosvis liberam esse navigationem," and supports it by an elaborate argument and quotations from the ancient poets, philosophers, orators and historians.578 This principle was not finally acknowledged by England as applicable to "The Narrow Seas" till 1805. Now, by international agreement, political domain extends only to one marine league from shore or within cannon range. The rest of the vast water area remains the unobstructed highway of the world.