He was an opportunist. Lemme tell you he didn't joined the uprising until a few weeks before it was carried out despite Leutenant Mola (the brains of the operation) and General Sanjurjo (who would have been put in charge) buttering him up for more tha a year.

He was very disliked and mistrusted by all other generals. But because he had most of the army under his command and got some decisive victories (again, opportunist) he got brownie points