Rather than resort to extreme measures again, however, the United States invoked the cooperation of the Hispanic republics and proposed a conference to devise some solution of the Mexican problem.

To give the proposed conference a wider representation, it invited not only the "A B C" powers, but Bolivia, Uruguay, and Guatemala to participate.

Meeting at Washington in August, the mediators encountered the same difficulty which had confronted their predecessors at Niagara Falls.

Though the other chieftains assented, Carranza, now certain of success, declined to heed any proposal of conciliation.

Characterizing efforts of the kind as an unwarranted interference in the internal affairs of a sister nation, he warned the Hispanic republics against setting up so dangerous a precedent.