Having joined the
Portuguese Communist Party (, he was arrested for the first time in March 1934, during a student demonstration in Lisbon, being released shortly afterwards. In total he would spend about twelve years as a prisoner of the regime, being incarcerated in several prisons, including
Aljube prison in Lisbon, now a Resistance Museum;
Caxias prison; the
Peniche Fortress; and in
Porto. In 1936 he was one of the first prisoners sent to
Tarrafal camp, a prison in the Portuguese
colony of Cape Verde, from which he was released in 1940, only to be returned there between 1943 and 1946. After being released in 1940 he resumed studies at the Faculty of Arts of the
University of Lisbon. He was one of the leaders of the students in 1941 when they protested against an increase in fees. In 1941 and 1942 he played an important role in the reorganization of the Portuguese Communist Party. He was arrested again in August 1942 and held in Caxias prison, from where he made a failed attempt to escape, being sent back to Tarrafal in June 1943. After release from Tarrafal, Soares, accompanied by his wife,
Maria Luísa Costa Dias, a doctor and also a communist activist, went to
Mozambique from 1947 to 1950, to help organize the communist party there. In 1953 he joined the Portuguese party's Central Committee, where he remained until his death in 1975. In 1954, he was again arrested and held in the prison of the
PIDE (International and State Defence Police) in Porto, from where he escaped, going underground and working to organize the Communist Party in the area to the south of Porto. In January 1960, he was arrested again, and held at the Peniche Fortress, being one of a group of nine to escape from there that included the Communist Party leader,
Álvaro Cunhal. He then went to
Algiers, leading the Patriotic National Liberation Front, which was an organization aiming to overthrow the Portuguese government. He returned to Portugal after the
Carnation Revolution of 25 April 1974, which overthrew the
Estado Novo, and was elected to the
Portuguese Parliament in the 1975 elections as a representative of the
District of Santarém. ==Death==