In September 1933, the Sergeants' Revolt, led by Sergeant Fulgencio Batista, overthrew Cespedes. A five-member executive committee (the Pentarchy of 1933) was chosen to head a provisional government. Ramon Grau San Martin was then appointed as provisional president. Grau resigned in 1934, leaving the way clear for Batista, who dominated Cuban politics for the next 25 years, at first through a series of puppet-presidents. The period from 1933 to 1937 was a time of "virtually unremitting social and political warfare".
A new constitution was adopted in 1940, which engineered radical progressive ideas, including the right to labour and health care. Batista was elected president in the same year, holding the post until 1944. He is so far the only non-white Cuban to win the nation's highest political office. His government carried out major social reforms. Several members of the Communist Party held office under his administration Cuban armed forces were not greatly involved in combat during World War II, although president Batista suggested a joint U.S.-Latin American assault on Francoist Spain in order to overthrow its authoritarian regime.