Since most high officers of the Spanish Republican Navy had joined the rebellion, Luis González de Ubieta rose rapidly both in rank and authority within the loyalist fleet.

Thus, at the beginning of the civil war, he became commander of the destroyer José Luis Díez and was sent to quell a minor conflict in Alicante when a group of rebel troops from Orihuela and smaller towns of the Vega Baja tried unsuccessfully to initiate a siege of the city.

Two months later, he was in charge of the cruiser Miguel de Cervantes, on which he took part in a naval operation that entered the Bay of Biscay (Expedición al Mar Cantábrico) in September and October 1936.

[6] Under Luis González de Ubieta's command, the Republican Navy concentrated on the protection of maritime convoys supplying the internationally isolated Spanish Republic, as well as the training of naval officers and their ships' crews.

[12] After the fall of Minorca, Luis González de Ubieta, who was the military governor of the island, fled to France on the Royal Navy cruiser HMS Devonshire with 452 other Republican refugees.

[13] From Marseille, he managed to reach Paris with his wife, while other Spanish Republican refugees were taken to Port Vendres and then interned in the Argelès-sur-Mer concentration camp by the French authorities.