Members of the Common Alternative Revolutionary Force (Farc) political party (from left)  Victoria Sandino, Pablo Catatumbo, Marco Calarca and Olmedo Ruiz, at the Capitol in Bogotá for the new Congress on Friday. Photograph:  Raul Arboleda/AFP/Getty Images

Half a century after their Marxist comrades took up arms in the Colombian mountains and vowed to overthrow the state, members of the country’s once-fe(...)