In the 1930s, Spain began building new modern minelayers, all named after Roman gods. The Júpiter-class ships were also meant to serve as gunboats and were equipped with good artillery armament for this purpose. While still under construction, the lead ship of the Júpiter class was captured by rebel nationalists. After her commissioning, the ship participated in the blockade of the Republican coast in the Bay of Biscay by intercepting transports and setting up minefields—the same minefields that would later cause the sinking of rebel battleship España.