Óscar Pérez Solís (24 August 1882 – 26 October 1951) was a Spanish artillery officer, engineer, journalist and politician.

[3] During World War I (1914–18) Pérez Solís supported the Allies, but was not deeply involved in their cause, having little interest in international affairs.

[4] On 8 March 1917 the Socialists of Valladolid declared a general strike in protest against the arrest of labor leaders a few days earlier.

[2] Francisco Largo Caballero said afterwards that the general strike in August had failed in part because the earlier attempt in Valladolid had drained energy from the movement.

[7] In early autumn of 1918 El Sol started to publish strongly worded articles by Pérez Solís.

He felt the a revolution would cause chaos and counter-revolution, and a republic would not have the support of the military, the middle classes or the working people.

[8] There he tried to find a position within the Basque labor movement, but would soon be affected by the mood of the region and start to move towards the far left.

Most of the leftist members thought at first they should stay with the PSOE, but Pérez Solís and Manuel Núñez de Arenas organized a split of the party.

[10] Pérez Solís read the manifesto of the new organization, the Spanish Communist Workers' Party (Partido Comunista Obrero Español, PCOE).

Pérez Solís was made editor of the party's journal La Bandera Roja (The Red Flag).

[11] Pérez Solís attended the XV congress of the Unión General de Trabajadores (UGT) in 1922 as representative of the farm workers of Bilbao.

[14] In August 1923 Pérez Solís tried to start a general strike in Bilbao at the same time as a rebellion by Basque troops who were being shipped from Málaga to Morocco.

[14] Pérez Solís continued his propaganda activity in Spain during the dictatorship of General Miguel Primo de Rivera that began in September 1923, and contributed to La Antorcha, the organ of the Spanish section of the Third International, published in Madrid.

He wrote several articles that favored the Confederación Nacional del Trabajo (CNT), at that time pro-Marxist but later anarcho-syndicalist.

[2] He was seriously injured on 23 August 1923 when assault guards entered the Bilbao Peoples House during a general strike called by the local communists.

[1] He was arrested on charges of being involved in violent protests against the shipment of troops to Morocco, and for an attempt to bomb the socialist newspaper El Liberal and its ideologue Indalecio Prieto.

At that time his sister arranged for him to meet the Jesuit priest Luis Chalbaud, a first step in a major change to his religious and political beliefs.

In the autumn there were rumors, later confirmed, that he had left the Communist Party, had again become a Catholic, and had accepted a management position in a major new company, the Compañía Arrendataria del Monopolio de Petróleos (CAMPSA).

[2] During the revolt of 18 July 1936 at the start of the Spanish Civil War (1936–39) Pérez Solís played a leading role for the Nationalist rebels.

After 48 hours he was released when the garrison rose in favor of the Nationalists, and joined the defense of the city against the Republicans as a captain under the command of Colonel Antonio Aranda.