On June 18, 1917,), at Cuautla, Mexico. Sidronio avenged his father by shooting Eufemio in the abdomen. He then threw his still living victim on an anthill. This event earned him the nickname, "el loco Sidronio" ("the crazy Sidronio").
Knowing Emiliano would want to avenge his brother, Sidronio sought out sanctuary with Zapata's enemies, the Carrancistas (followers of Venustiano Carranza), who granted him an amnesty.