A few years later--in 1837--Peru fell into a dispute with Chile on account of the Guano provinces of Atacama and Tarapaca. Peru was again invaded, but eventually the Chileans abandoned the country and returned to their own. After this, no little confusion prevailed in the internal affairs of Peru. Various leaders came, fought, and went, until civil war was followed by a conflict with Bolivia, in the course of which Gamarra, the Peruvian President, was killed, and the Peruvian forces were totally defeated in 1841. In 1845 there seemed a prospect of improvement in the affairs of the Republic, when Ramon Castilla was elected President. Castilla was a man of strong and progressive views, and commerce began to flourish under his guidance. He was followed by President Echenique, but returned to public life, and succeeded the latter as President after a lapse of ten years, in the course of which considerable official corruption had been shown. In 1864 occurred the first collision with Spain since the conclusion of the war of liberation. In that year Spain sent out Admiral Pinzon to the Pacific coast in command of three war vessels. The objects of the expedition were avowedly scientific, but it met with a suspicious reception from the first on the Pacific coast. The conduct of Admiral Pinzon decidedly did not tend to allay any anxiety on the part of the Republicans. Both Peru and Chile felt that their independence was endangered, and prepared to resist. On April 14, 1864, the Spanish vessels gave the signal for war by seizing the Chincha Islands. Hostilities, however, were staved off for a while by the action of the Spanish authorities, who stated that Admiral Pinzon had exceeded his instructions. In the meanwhile the capture of one of his smaller vessels by the Chileans had so preyed upon the Admiral's mind that he committed suicide. He was succeeded in his command by Admiral Pareja. At the beginning of 1866 war with Spain was officially declared. The Spanish fleet had now been strongly reinforced, and some naval engagements took place between the Spaniards and the allied Peruvians and Chileans, in the course of which the Spanish squadron was repulsed. On April 25 the Spanish vessels, having already attacked Valparaiso, appeared before Callao, and a week later they began vigorously to bombard the town, which returned the fire. In this engagement both land and sea forces suffered considerably. After this the Spanish fleet sailed back to Europe, and the war came to an end. Peace, however, was not declared for two years afterwards.