[Sidenote:  Political detachability of islands.]

Islands are detached areas physically and readily detached politically.  Though insularity gives them some measure of protection, their relatively small size and consequently small populations make them easy victims for a conquering sea power, and easy to hold in subjection.  The security of an island habitat against aggression therefore, increases with its size, its efficiency in naval warfare, and its degree of isolation, the last of which factors depends in turn upon its location as thalassic or oceanic.  Islands of enclosed seas, necessarily small and never far from the close encircling lands, are engulfed by every tide of conquest emanating from the nearby shores.  Oesel and Dago have been held in succession by every Baltic power, by the Teutonic Orders, Denmark, Sweden and Russia.  Gotland has acknowledged allegiance to the Hanseatic League, to Denmark and Sweden.  Sardinia, occupying the center of the western Mediterranean, has figured in a varied series of political combinations,—­with ancient Carthage, Rome, the Saracens of North Africa, with Sicily, Pisa, Aragon, Piedmont, and finally now with united Italy.[877] To the land-bred Teutonic hordes which swept over western Europe in the early centuries of our era, a narrow strip of sea was some protection for Sicily, Corsica, Sardinia, Malta and the Balearic Isles.  Hence we find these islands slow in succumbing to their non-maritime conquerors, and readily regained by the energetic Justinian.  Later they fell victim to the sea-wise Saracens, but again gravitated back to their closer and more natural European connections.

[Sidenote:  Insular weakness due to small area.]

More often the small area of an island facilitates its retention in bondage, when the large and less isolated continental districts have thrown off an unwelcome yoke.  Athens, with her strong navy, found it an easy task to whip back into the ranks of the Delian Confederacy her recalcitrant island subjects like Naxos, Samos and Thasos; but her mutinous cities in peninsular Chalcidice and isthmian Megara, incited to revolt and aided by their neighbors,[878] were less at her mercy.  This principle was recognized by Thucydides,[879] and taken advantage of by the Lacedaemonians during the great war for Spartan supremacy.  England has been able to hold Ireland in a vise.  Of all her former French territory, she retains only the Channel Isles.  Cuba and Porto Rico remained in the crushing grasp of Spain sixty-four years after Mexico and the continental states of Central and South America, by mutual help and encouragement, had secured independence.  The islands found that the isolation which confers protection from outside aggression meant for them detachment from friendly sources of succor on the mainland.  The desultory help of filibuster expeditions, easily checked at the port of departure or landing, availed little to supplement the inadequate forces of rebellion pent up on their relatively small areas.  By contrast, Mexico’s larger area and population, continually stirred by American example and encouragement, reinforced by American volunteers and even by United States army officers, found revolt from 1812 to 1824 a comparatively easy task.