King Alfonso XIII became king of Spain upon his birth in 1886. Up until 1923, Spain was a constitutional monarchy - Alfonso was head of state but was expected to work with the Cortes (Spanish Parliament). Instead, Alfonso worked closely with the Spanish military elite and was reluctant to introduce reforms that would shift power away from the traditional ruling class towards ordinary Spanish people. Alfonso backed Primo de Rivera's coup in September 1923 which saw the overthrow of the constitutional government and the establishment of a repressive military dictatorship. Alfonso's support for Primo de Rivera's regime made the monarchy extremely unpopular, allowing for republican parties to grow in support. Alfonso XIII was eventually forced to flee Spain in April 1931 after the success of republican parties in the Spanish municipal elections of that year. Alfonso never officially abdicated but his departure from Spain opened the way to the establishment of a democratic republic.