The Spanish Navy Marines (Infantería de Marina) was labelled as a "colonial force" in the early days of the Spanish Republic because of the high-profile role it had had in the unpopular 1920–1926 wars in North Africa.
Newly nominated Minister of War Manuel Azaña planned eventually to disband the marine corps as part of his hasty reforms of the Spanish armed forces.

However the Civil war began before the Infantería de Marina was officially disbanded and in October 1936 the War Ministry was replaced by the 'National Defence Ministry' (Ministerio de la Defensa Nacional), led by the prime minister, Largo Caballero.
Thus the Spanish Republican Navy Marines of the areas of Spain that had remained loyal to the government were not disbanded and became part of the new military structure of the republic.
At the republican naval base of Cartagena the Tercio de Levante Marine corps was garrisoned and used mainly for guarding moored ships and naval facilities, as well as for manning anti-aircraft guns.

Some republican Infantería de Marina units also saw frontline combat action; the 151 Brigada Mixta, was a mixed brigade composed of Spanish Republican Navy Marines led by Commander Pedro Muñoz Caro.
Its landing operations activity was limited, however, by the lack of offensive actions and the general ineffectiveness of the Spanish Republican Navy.
Therefore, these Republican Marines saw action mostly inland supporting the Army in such battles as the Battle of Alfambra, Battle of Brunete, Battle of the Ebro and the Battle of the Segre, far away from the sea.
Photographer Robert Capa took pictures of the Spanish Republican Navy Marines in one of these inland battles.

Republican Infantería de Marina Lieutenant Colonel Ambrosio Ristori de la Cuadra, killed in action during the Siege of Madrid, was posthumously awarded the Laureate Plate of Madrid.
The Spanish Navy Marines (Infantería de Marina) was labelled as a "colonial force" in the early days of the Spanish Republic because of the high-profile role it had had in the unpopular 1920–1926 wars in North Africa. Newly nominated Minister of War Manuel Azaña planned eventually to disband the marine corps as part of his hasty reforms of the Spanish armed forces.
However the Civil war began before the Infantería de Marina was officially disbanded and in October 1936 the War Ministry was replaced by the 'National Defence Ministry' (Ministerio de la Defensa Nacional), led by the prime minister, Largo Caballero. Thus the Spanish Republican Navy Marines of the areas of Spain that had remained loyal to the government were not disbanded and became part of the new military structure of the republic. At the republican naval base of Cartagena the Tercio de Levante Marine corps was garrisoned and used mainly for guarding moored ships and naval facilities, as well as for manning anti-aircraft guns.
Some republican Infantería de Marina units also saw frontline combat action; the 151 Brigada Mixta, was a mixed brigade composed of Spanish Republican Navy Marines led by Commander Pedro Muñoz Caro. Its landing operations activity was limited, however, by the lack of offensive actions and the general ineffectiveness of the Spanish Republican Navy. Therefore, these Republican Marines saw action mostly inland supporting the Army in such battles as the Battle of Alfambra, Battle of Brunete, Battle of the Ebro and the Battle of the Segre, far away from the sea. Photographer Robert Capa took pictures of the Spanish Republican Navy Marines in one of these inland battles.
Republican Infantería de Marina Lieutenant Colonel Ambrosio Ristori de la Cuadra, killed in action during the Siege of Madrid, was posthumously awarded the Laureate Plate of Madrid.
Spanish Republican Navy