In a musky smelling underground room, deep under the decommisioned Vickers guns at the Bateria de Castillitos (Cabo Tiñoso), is part of the Auxiliary Engine – Petter 25HP. The system included four of the largest artillery pieces ever made – huge 38.1 Vickers guns with a range of some 20 miles. These guns remain in place, two here at the Castillitos battery, at Cabo Tiñoso, near Puerto de Mazarron, and not far away, two at the Cenizas battery, near La Manga Club. This engine was situated in a motor house under the 381/45 gun. It was used for starting the dynamo which generated 24 volts DC for lighting in the guns and magazines, for a compressor which supplied accumulators for starting, refilling the recoil mechanism of the gun and to power refrigeration equipment.