The resignation of President Diaz in May, 1911, was accepted as a proof of the popular character and the success of the revolution, and Madero, who was elected president in October, was promptly recognized as the constitutional head of the Mexican Government.

The revolution, however, aroused the United States to the fact that there still persisted the era of disturbance which it had hoped was drawing to a close in Latin America.

With this disturbing revelation in mind, Congress took another step in the development of American policies consequent upon the Monroe Doctrine by passing an act authorizing the President, whenever he should "find that in any American country conditions of domestic violence exist which are promoted by the use of arms and munitions of war procured from the United States," to prohibit trade in such articles.

Under this authority, President Taft promptly forbade the export of such articles to Mexico except to the Government.
Real revolutions, however, seldom result simply in the transfer of authority from one group to another.

The breaking of the bonds of recognized authority releases all sorts of desires, represented in the state by separate groups, each of which sees no reason for accepting the control of another.