January 1860, Prat boarded, for the first time, Esmeralda. His nautical apprenticeship continued: embarkation and disembarkation, combat simulation, etc. In July 1861, he left the Naval Academy as "primera antigüedad" (the most distinguished in the course). He obtained the grade of "midshipman without examination". During this period, Prat distinguished himself in an incident involving Infernal, a French ship that was carrying explosive materials. On October 1, 1861, it caught on fire while in the Bay of Valparaíso. Esmeralda, which was nearby, sent boats to save the wreck, one of which was steered by Prat, who would struggle for two hours against the fire. War with Spain On July 21, 1864, Arturo Prat passed the theoretical and practical test needed to be promoted from "midshipman without exam" to "examined midshipman". That year saw the incidents that resulted in the war against Spain, inflamed by the Chilean attitude towards the occupation of the Peruvian Chincha Islands by a Spanish squadron. The resulting war would prove to be a baptism of fire for Prat and his classmates. Commanding Esmeralda at the time was Juan Williams Rebolledo, who planned the recovery of the Chilean steamer and the capture of the Spanish schooner Covadonga. The naval battle of Papudo occurred on December 26 and rapidly went the way of the Chilean force which was superior in firepower and was able to defeat and capture the ship. The capture of Covadonga resulted in the promotion by one grade of all sailors participating in the battle, converting Prat into an ensign (equivalent to a second lieutenant in the army). Wishing to offset their losses at Papudo, the Spanish fleet sought another confrontation with the allied navies (Peru and Ecuador added to Chile's side), leading to the inconclusive battle of Abtao at Chiloé on February 7, 1866. Artillery combat occurred only between Covadonga and the Spanish ships Villa de Madrid and Blanca, as the other allied ships were unused due to a lack of coal and the rocky estuary. Prat then served on Covadonga, the ship which resisted the Spanish bombardment. There were no losses on the allied side, while the Spanish suffered two deaths. Young officer After the war, Prat completed a large number of sea voyages, both inside and outside his country, including voyages to the Juan Fernández Islands, Easter Island (on the corvette Esmeralda under Policarpo Toro's command), Magallanes and Peru. During the latter trip