Constitutional Army
It was formed in March 1913 by Venustiano Carranza , so-called "First-Chief" of the army , as a response to the murder of President Francisco I . Madero and Vice President José María Pino Suárez by Victoriano Huerta during "La Decena Trágica" ( Ten Tragic Days ) of 1913 , and the resulting usurpation of presidential power by Huerta . 
<triplet> Francisco I. Madero <subj> President <obj> position held <triplet> Victoriano Huerta <subj> President <obj> position held