Career
Laid down:	1862
Launched:	1 August 1863
Commissioned:	16 April 1864
Decommissioned:	1877
Fate:	Sold 19 February 1908
Struck:
General Characteristics
Displacement:	1,034 tons
Length:	225 ft
Beam:	43 ft 8 in
Draught:	13 ft 6 in
Propulsion:	Steam engine
Speed:	7 kts
Complement:	85 officers and enlisted
Armament:	2 15" D. sb.

The first USS Canonicus was a single-turret monitor in the United States Navy during the American Civil War. She was originally named for Canonicus, a chief of the Narragansett Indians. She was briefly named Scylla.

Canonicus was launched 1 August 1863 by Harrison Loring , Boston, Massachusetts, and commissioned 16 April 1864 at Boston, Commander E. G. Parrott in command.

Canonicus sailed from Boston 22 April 1864 and arrived at Newport News, Virginia, 3 May for service with the James River Flotilla . Her heavy guns pounded Confederate batteries at strong points along the James on 21 June, 16 August, and 5-6 December.

Reassigned to the North Atlantic Blockading Squadron, the monitor arrived at Beaufort, North Carolina, 15 December 1864, and took part in the heated attacks on Fort Fisher, North Carolina. In the first engagement on 24 and 25 December, Canonicus was hit four times, but suffered no casualties and only minor damage while her own fire put two guns of Fort Fisher's battery out of action. On 13 January 1865, during the second attack, Canonicus received 36 hits. Twice her flag was shot away, twice replaced. None of her men was killed, and only three wounded. Again, she dismounted two of the Fort's guns.

In February 1865, Canonicus joined the South Atlantic Blockading Squadron off Charleston, South Carolina, and during the closing months of the war aided in the capture of several blockade runners off the South Carolina coast, as well as voyaging to Havana, Cuba, in search of CSS Stonewall.

The monitor entered Philadelphia Navy Yard 25 June 1869, and was decommissioned 5 days later. Renamed Scylla 15 June 1869, she was reassigned her former name 10 August 1869. Recommissioned 22 January 1872, Canonicus cruised in coastal waters in the Atlantic and Gulf of Mexico when not out of commission, as she was frequently during this time. Her final decommissioning took place at Pensacola, Florida, in 1877, and she performed no further service until sold 19 February 1908.

See USS Canonicus for other ships of this name.