In these speeches, Cruz sometimes admits — with disbelief — that he once supported Fidel Castro’s revolution. “I started speaking at different rotary clubs around Austin, Texas — in favor of Castro! I still thought he was the savior of the country,” he told FreedomWorks, a conservative group, in 2013. Local news articles and documents from the late 1950s offer a clearer picture of the days of Cruz as a young man, then a believer in the revolution and a visible college activist. On Jan. 8, 1959, Fidel Castro rode victoriously into Havana. The country’s dictator, Batista, had fled a...