Tiamzon's efforts for the Leftist movement began in the 1970s when he organized labor unions for market vendors and workers in Marikina and Caloocan. In 1972, he was arrested after then-President Ferdinand Marcosdeclared martial law. Detained in Fort Bonifacio, he managed to escape and remained a fugitive until his 2014 arrest. In the 1970s Tiamzon was sent to Samar to provide "political redirection" for the NPA cadre there. In 1975 he became the Secretary of the CPP's Eastern VisayasRegional Party Committee. In 1976, the CPP issued an organizational document that guided the movement's work in the countryside; Tiamzon was believed to have been responsible for writing most of that document, drawing on his vast experience in Samar. Other former posts include commands of the CPP's Southern Luzon Commission and Sorsogon Regional Mobile Force, and secretary of the CPP's National Commission for Mass Movement. According to the Armed Forces of the Philippines, Tiamzon was involved in many of the CPP's major activities since 1987 when Jose Maria Sison, the CPP's founding chairman, went into exile in the Netherlands. Tiamzon consolidated the CPP in the 1990s after it suffered a split as a consequence of the Second Great Rectification Movement. He formally became the party's Chairman between 2004 and 2008. Tiamzon along with his spouse, a fellow senior member of the CPP leadership, and five other persons were arrested by Philippine security forces in Cebu in 2014 during the presidency of Benigno Aquino III; they had been exposed by surveillance since relief operations began in the wake of Typhoon Haiyan the year before. Recovered in their possession were firearms, grenades and ammunition. The Tiamzons were wanted on murder charges as a consequence for their alleged involvement in the deaths of fifteen civilians whose remains were discovered in a mass grave in Inopacan, Leyte in 2006. They were released from detention in August 2016 upon the order of President Rodrigo Duterte as they were designated representatives of the National Democratic Front to the peace talks with the Government of the Philippines to be held in Oslo, Norway. Duterte announced that peace negotiations would no longer be undertaken in February 2017 and that he expected the NDF representatives, including the Tiamzons to "on their own… return and go back to prison."
Personal life
Benito is married to Wilma Tiamzon, the Secretary-General of the CPP-NPA. The couple have two children, Liza and Alex, and six grandchildren. According to a source, Benito has six toes on one of his feet, a condition known as polydactyly.
