Even if the policing of the high seas should be placed by the international authority in the hands of Great Britain, its past record shows that it may be trusted; and in any case its own interest in the free and unimpeded passage of commerce upon the seas is a guarantee that it would discharge its office effectually. Still, it is probably not desirable that the control of the seas should be devolved upon a single power. The universal interests of the nations in the franchise of the ocean highways make it necessary that their protection be an international obligation. This part of the problem should, however, present no insuperable difficulty. In practice the high seas are to all intents and purposes already neutralised. Our difficulties arise when we come to the question of narrow inter-ocean waterways. The most conspicuous, though perhaps not the most important, case of this type, is the water connecting the Black and the Ægean Seas; and the obvious solution lies in the permanent neutralisation of the Bosphorus, the Sea of Marmora and the Dardanelles. There is no difficulty involved in the institution of an international commission to carry this project into effect. This particular outlet affects so many nations that it is intolerable that it should remain the particular property of a single nation; and the only possible alternative is this of neutralisation under international commission. The straits of Gibraltar present a different though a no more difficult problem. With the development of modern ordnance, the military and political importance of the Rock of Gibraltar has virtually disappeared; and its value is chiefly that of a naval base and coaling station. It is difficult to see what purpose under modern conditions the retention of a kind of British sovereignty in the Straits serves. In the days when the route to India had to be protected, it was of course another story; and there is really no reason why the Straits of Gibraltar—as well as all other narrow waterways—should not be neutralised in perpetuity under international guarantee. The experience of the present war in the matter of submarine attacks on merchant ships in the Mediterranean showed how ineffectual any guardianship of the Straits is likely to be in the future; and the same thing is true of all waterways which are not sufficiently narrow to be swiftly barred against entrance by submarine craft.