Oh, thanks Novice, Hood and Eswube! Your feedback, and the support of Colombamike are as important as the drawings!
A very active class of gunboats, Canovas del Castillo class, was ordered in early 1920s, and saw action in almost every important action in the war of Morocco, including the crucial Alhucemas landings in 1926. In July 1936, Canalejas and Canovas del Castillo were at anchor at Cadiz and Dato was in Ceuta, so the 3 vessels were in the rebel (francoist) side; unlike most of the Fleet (2 active cruisers, all the destroyers except Velasco, all the submarines) which remained in hands of the republican goverment. The most professional part of the Spanish Army was the Army of Africa (mainly in Northen Morocco) and passing troops and artillery was a critical issue in the first weeks of the war, and the air bridge (mainly Junkers trimotors) was unable to transport heavy loads, but as a strong republican squadron was patroling the straits, any reinforment by sea was a risky operation.
The first week of August 1936, a convoy formed by 2 small transports escorted by Dato, an armed trawler and an old torpedo boat from Algeciras, cross the straits and landed 2 infantry battalions and a 105 mm battery, despite de opposition of the much superior Alcala Galiano republican destroyer (1). While in Algeciras, a republican squadron leaded by Jaime I battleship, shelled that harbour and Dato was sunk resting in shallow waters. Late in september, the gunboat was refloated and towed to Cadiz for a complete refit.
The bridge structure was deeply modified, the forward 102 mm guns now were superflying and all had longer shields, the 47 mm Vickers guns were replaced by 76 mm Ansaldo AA guns, suplemented by 2 x 20 mm Scotti automatic guns. Two depth charges were carried both port and starboard. The other vessels were modified in the same way as soon as possible (Canalejas, the first half of 1937). The class was active in the blocade of the republican mediterranean coast until the end of the war. During WWII the 3 vessels of the class were between Cadiz and the colonies at North and Equatorial Africa.
The final part of the career of the 3 vessels was at the Spanish Guinea. All these ships were paid of in the 1950s.
Credits: Once again, Colombamike helped me with superb blueprints and accute comments for improving the drawings. Thanks a lot! Cheers.
(1): Please, check that in that stage of the war, the rebel gunboat was flying the republican flag. The SCW was deeply over simplified as a war between fascist and communist ideologies, but both sides were in fact, an amalgam of a very complex composition.