When Tucker entered the Navy of Peru, that Republic was engaged in a war with Spain. Spain had never recognized the independence of her former South American colonies, and thinking a favorable opportunity had arisen for asserting her dormant claims, the Spanish Government sent an iron-clad frigate, accompanied by several smaller vessels, to attack the Chilean and Peruvian seaport cities on the Pacific coast. The attack upon Valparaiso, the chief port of Chile, was successful, but the Spanish squadron was beaten off at Callao by the Peruvian batteries. Whilst preparing for the defense of Callao, the Peruvian Government determined to place its naval establishment on such a footing that it would be able to meet any force Spain could send to the Pacific. Tucker had, and most deservedly, the reputation of being a hard fighter, a thorough disciplinarian, and a splendid seaman; hence the Peruvian Government of President Prado directed its Minister at Washington to engage his services if possible. The cause was one which enlisted all Tucker's sympathies, and he agreed to take command of the Peruvian fleet. Tucker became much attached to Peru, and served the Republic zealously and faithfully. He had many warm friends in Lima, and no matter what party held the Government, the trust and confidence reposed in him by the authorities in Lima was always implicit. Tucker arrived in Lima accompanied by his personal staff, David Porter McCorkle, captain of the fleet, and Walter Raleigh Butt, commander and aide. Just before their leaving New York the Peruvian Minister handed Tucker a bag of gold, with which he was told to pay all the traveling expenses of himself and staff; this was done, but when the party arrived at Lima the bag was still half full. Tucker insisted on returning this surplus to the Government, but there was no precedent for such a thing, and it was not without some difficulty that there could be found an officer of the treasury authorized to receive and receipt for the unexpected money. The appointment of a foreigner to command their fleet was distasteful to some of the Peruvian officers, and this fact coming to Tucker's knowledge, he informed General Prado, the President of the Republic, that he had no wish that any officer should be forced to serve unwillingly under his command, and preferred resigning if the dissatisfaction at the appointment of a stranger to command the fleet was general or deep-seated. The officers who were dissatisfied were relieved from duty, and others were easily found who were not only willing but anxious to serve under Tucker. The Peruvian squadron was lying at Valparaiso when Tucker hoisted his flag on board the frigate _Independencia_. The Chilean squadron was also lying at Valparaiso, and Tucker, as senior officer present, was in command of the allied fleets of both Peru and Chile.