For nearly a hundred years we have successfully upheld the Monroe Doctrine without resort to force. The policy has never been favorably regarded by the powers of continental Europe. Bismarck described it as "an international impertinence." In recent years it has stirred up rather intense opposition in certain parts of Latin America. Until recently no American writers appear to have considered the real nature of the sanction on which the doctrine rested. How is it that without an army and until recent years without a navy of any size we have been able to uphold a policy which has been described as an impertinence to Latin America and a standing defiance to Europe? Americans generally seem to think that the Monroe Doctrine has in it an inherent sanctity which prevents other nations from violating it. In view of the general disregard of sanctities, inherent or acquired, during the past few years, this explanation will not hold good and some other must be sought. Americans have been so little concerned with international affairs that they have failed to see any connection between the Monroe Doctrine and the balance of power in Europe. The existence of a European balance of power is the only explanation of our having been able to uphold the Monroe Doctrine for so long a time without a resort to force. Some one or more of the European powers would long ago have stepped in and called our bluff, that is, forced us to repudiate the Monroe Doctrine or fight for it, had it not been for the well-grounded fear that as soon as they became engaged with us some other European power would attack them in the rear. What other satisfactory explanation is there for Louis Napoleon's withdrawal from Mexico, for Great Britain's backdown in the Venezuelan boundary dispute, and for the withdrawal of the German fleet from Venezuela in 1902?