Álvaro Obregón Salido
Álvaro Obregón Salido, a general of the Mexican Revolution who had lost his arm in combat, fled Mexico City due to a plot started against him by President Carranza which falsely accused him of plotting a military coup. Obregón was running for President against Carranza's choice, Ignacio Bonillas.
Obregón was considerably to the left of Carranza and had a knack for joining movements before their success was assured but which were on the ultimately successful side. The son of a once wealthy man who had lost his wealth by choosing to support Maximilian during the French occupation of Mexico, he was a brilliant and inventive man who was principally a farmer by trade but also an inventor, having invented a chickpea harvester that was widely successful.
Obregón flight from Mexico City, disguised as a railroad employee, followed a series of indignities imposed upon him by Carranza, including the loss of his military rank. His departure on this date indicated a dangerous new twist in unstable Mexican politics as Carranza's government was not stable and Obregón was capable.
And he was already not without potential allies.
The Mexican state of Sonora had gone into rebellion against the Carranza government.
Aldolfo de la Huerta
Sonora's Governor was the former Mexican Revolutionary general Aldolfo de la Huerta who was also tangling with Carranza, even though Carranza had only recently considered him as his replacement. Much of that had to do with De la Huerta's view that Sonora, as a Mexican state, should be allowed to run much of its own affairs while Carranza took a more centrist Federalist view and was in fact directly interfering with things in Sonora.
Sonora, therefore, declared its independence from Mexico, although that goal wouldn't last long. The potentail
What would last for a considerably long time was the unstable period of Mexican governments. The revolution had started to consume its own.