Álvarez was born in Noveleta, Cavite. He received formal schooling at the San José College in Manila, and obtained a teacher's diploma. He returned to Cavite and worked as a schoolteacher in Naic and Maragondon. In 1871, he was incarcerated and tortured by the colonial authorities after insulting a Spanish soldier. The following year, he was accused of involvement in the Cavite Mutiny and was hauled to Manila in chains for detention. Upon his eventual release, he returned to Noveleta, and in 1881, was elected capitan municipal, a position he held until the outbreak of the Philippine Revolution in 1896.
Álvarez and his son Santiago were active members of the Katipunan, the anti-Spanish secret society founded by Andrés Bonifacio in 1892. Mariano was the uncle of Bonifacio's wife, Gregoria de Jesús. In early 1896, Álvarez was elected president of the Magdiwang, one of two Katipunan branches in Cavite along with Magdalo. The two branches evolved into separate factions with their own local governments, through their provincial councils. Álvarez helped facilitate growing membership of the Katipunan in Cavite. When the revolution started in August 1896, Bonifacio at least planned to give him overall command of all the revolutionary forces in Cavite. A draft of the appointment order survives but whether it was dispatched is uncertain. He led Filipino forces in several battles against the Spanish army in Cavite and held the rank of general. His efforts helped liberate most towns in Cavite from Spanish control within weeks from the start of the revolt. He was recognized as the instigator of the revolution in Cavite. Rivalry and tension existed between the Magdiwang and Magdalo factions over jurisdiction and authority, and Álvarez, as Magdiwang head, invited Bonifacio, as Presidente Supremo of the Katipunan, to meditate over them. Bonifacio was seen as partial to the Magdiwang probably due to his kinship ties with Álvarez. In their memoirs, Emilio Aguinaldo and other Magdalo personages claim that Bonifacio became the head of the Magdiwang, receiving the title Hari ng Bayan with Álvarez as his second-in-command. However, no documentary sources have been found substantiating these claims. Instead it has been suggested that these claims stem from a misunderstanding or misrepresentation of one of Bonifacio’s titles, Pangulo ng Haring Bayan. In his own memoirs, Santiago Álvarez clearly distinguishes between the Magdiwang government and the Supreme Council of the Katipunan headed by Bonifacio. The dispute between the Magdiwang and Magdalo soon involved the issue of command of the revolution. The Magdalo called for the abolition of the Katipunan and the establishment of a revolutionary government. Bonifacio and the Magdiwang maintained the Katipunan was already their government. After losing the internal power struggle to Aguinaldo, Bonifacio was executed in 1897. Álvarez was aggrieved by Bonifacio's death, and, like Emilio Jacinto, refused to join the forces of Aguinaldo, who had then retreated to Biak-na-Bato in Bulacan.
Personal life
In May 1863, he married Nicolasa Virata y del Rosario; their only child, Santiago, also a revolutionary general, was born on July 25, 1872 in Imus.
