Five years and more than 35,000 deaths into Mexico’s bloody drug war, two cartels have emerged as the dominant force in narcotics and the two are poised to slug it out in a dangerous battle for control; the Mexican governmen’s crackdown on the drug cartels has left many gangs splintered and operationally less effective without their leaders; in the ensuing power vacuum, the Zetas and Joaquin “El Chapo” Guzman’s Sinaloa cartel have stepped up as the two leading gangs.