Canonicus-class monitor

The Canonicus-class monitor was a class of nine monitors built for the Union Navy during the American Civil War. They saw service in the Civil War and the Spanish–American War, although two of them were never commissioned.

They were basically improved Passaic-class monitors, modified in accordance with war experience. The four ships not commissioned during the war were built on the Ohio River, three at Cincinnati, and Manayunk as far up as South Pittsburgh.

Design
The hull lines were improved and designed speed is given as 13 kn but there was no hope of getting near this. The 5 x side armour was backed by two iron stringers 6+1/2 in deep and 6 in thick for 70 ft from the bows, but 4 in elsewhere, and the armour lower edge was 3 ×. The turret, of 21 ft internal diameter, had 10 × plates as did the pilot house above, and the funnel base was also armored. The turret skirt was protected by a 5 in thick and 15 in high ring fixed to the turret, and as in other later monitors the 15 in guns were longer than in the Passaic class and fired with their muzzles outside the turret.

Tecumseh was sunk during the Battle of Mobile Bay by a mine. Canonicus, the last survivor, was decommissioned 31 years before being sold. Catawba and Oneota were both sold to Peru, on 2 April 1868, without ever entering service in the US Navy. Renamed by the Peruvian Navy as Atahualpa and Manco Capac respectively, they participated in the War of the Pacific, which lasted from 1879 to 1883.