USS Pennsylvania (ACR-4)

The USS Pennsylvania (ACR-4) (Armored Cruiser No. 4) was the lead ship of her class. The armored cruiser was a type of warship of the late 19th and early 20th centuries, designed like other types of cruisers to operate as a long-range, independent warship, capable of defeating any ship apart from a battleship, and fast enough to outrun any battleships it encountered. It was distinguished from other types of cruiser by its belt armor-thick iron (or later steel) plating on much of the hull to protect the ship from shellfire from enemy guns, much like the protection method of battleships. In 1908 the armored cruiser was supplanted by the battlecruiser which, with armament equivalent to that of a dreadnought battleship and steam turbine engines, was faster and more powerful than armored cruisers. At around the same time, the term 'light cruiser' came into use for small cruisers with armored belts. Despite the fact they were now considered second-class ships, armored cruisers were widely used in World War I. Most surviving armored cruisers from this conflict were scrapped under the terms of the Washington Naval Treaty of 1922.

USS Pennsylvania was laid down in 1901 and commissioned on 9 March 1905. She initially operated in the Atlantic until 1906 when she departed for the Asiatic station, returning to San Francisco in September 1907. On 18 January 1911, a plane flown by Eugene Ely from the Tanforan airfield in San Bruno, California landed on a platform constructed on her afterdeck. This was the first successful aircraft landing on a ship, and the first using a tailhook apparatus, thus opening the era of naval aviation and aircraft carriers.

While in reserve at Puget Sound from 1 July 1911-30 May 1913, the cruiser trained naval militia. She was renamed Pittsburgh on 27 August 1912 to free the name "Pennsylvania" for a new battleship. As Pittsburg, she patrolled the west coast of Mexico during the Mexican Revolution and remained in the Pacific during World War I. She was designated as the flagship for Commander, U.S. Naval Forces in the eastern Mediterranean and departed from Portsmouth NH for such duties in June 1919. She served in various assignments in the Atlantic, Mediterranean and Pacific waters  prior to decommissioning and scrapping in 1931.

© Richard Tripp 2012