Pareja was sent to the Pacific in 1864 to relieve Admiral Luis Hernández-Pinzón Álvarez, whose seizure of the Chincha Islands was disapproved in Madrid.
As his demands for satisfaction were refused, he declared war against Chile on the 24th, and proceeded to blockade the principal Chilean ports.
On November 17 an armed launch of the frigate Resolution was captured by the Allied steamer Independencia near the port of Talcahuano.
He could make no positive advances in his war with Chile, his blockade deteriorated, became ineffective and the crews of the ships became demoralized.
The next day, November 28, Admiral Pareja dressed in his best uniform, laid down on his bed, and shot himself in the head on board his flagship, the screw frigate Villa de Madrid, off Valparaiso.