HMS Vigilant ( 1777 ) HMS " Vigilant " was a merchantman converted into a warship during the American Revolution . After serving as a transport in North American waters from 1775 , she was purchased by the Royal Navy ( RN ) and modified for shore bombardment duties in 1777 . She was instrumental in the eventual British success during the siege of Fort Mifflin that same year and supported British operations in Georgia and South Carolina in 1779 – 80 . Her heavy armament proved to be more than " Vigilant " was designed to handle and she was condemned and disposed of in 1780 . Description and service . Built at Whitby in 1774 , the ship was named the " Grand Duchess of Russia " and she was chartered by the Navy Board to serve as a transport at the beginning of 1775 . While being modified at Deptford Dockyard in February , the ship was surveyed and found to be barque - rigged and just over 308 tons burthen in size . A survey in New York two years later gave her length as , measured at the keel , with a beam of . Naval historian Rif Winfield quotes her tonnage as 684 burthen with a length at the gundeck of and beam of . " Grand Duchess of Russia " departed for Boston , Massachusetts carrying 150 marines on 30 March 1775 and she remained in North American waters for the next two years . Vice Admiral Lord Howe , commander of the North American Station , informed the Admiralty on 23 April that he had purchased the " Grand Duchess of Russia " and commissioned her as HMS " Vigilant " to bombard targets ashore . The ship received fourteen 24 - pounder guns from the 50 - gun ship and two 9 - pounder and four 6 - pounder guns from the hospital ( prison ) ship . Additional gun ports were cut in " Vigilant " s side to allow two guns to be switched from one side to give her a broadside of nine guns . The 150 men of her crew were made up from the crews of Howe ' s flagship , the third rate , " Centurion " , and the fourth rate while her 30 marines were drawn from the marine brigade at Halifax . Her conversion was completed by the end of June and her first task was to cover the evacuation of British troops from Perth Amboy , New Jersey on 29 July . The following month , " Vigilant " served as Howe ' s flagship when he landed British troops at Elkton , Maryland , at the northern end of Chesapeake Bay , during the Philadelphia Campaign . In October , the ship sailed for the mouth of the Delaware River to attack the American fortifications defending Philadelphia . During this voyage , she rolled so badly during heavy weather that the round shot fell out of her guns and it was later decided that she should not put to sea with her guns mounted except during the summer months . " Vigilant " was not designed to carry such heavy weights as the 24 pounders up high in the ship and cutting gun ports in her sides further weakened her structure . The first attack on Fort Mifflin on 22 – 23 October had been a disaster with two British ships run aground and burnt . For the second attack three weeks later , " Vigilant " s crew was reinforced with an extra 50 men to work the guns and 24 riflemen to suppress the defenders of the fort during the attack . The ship ' s sides were reinforced and two guns were transferred to the starboard side of the ship . Her trim was maintained by placing casks of water on the port side . While other ships bombarded the fort from the main channel , " Vigilant " and a smaller ship worked their way up a secondary channel to the rear of the fort . They were able to silence the fort ' s guns by 6 p . m . , and the Americans evacuated five hours later , despite the ship ' s grapeshot and small arms fire . During the attack " Vigilant " only lost three men killed and five wounded ; her hull had only been hit several times , but her rigging was shot to pieces . In recognition of the ship ' s success , her commander , Lieutenant John Henry , was promoted to the command of the frigate . " Vigilant " was generally inactive while the British occupied Philadelphia , but she sailed to New York City when the British evacuated the city in June 1778 . She joined the small British squadron there upon the approach of a French squadron under the command of the Comte d ' Estaing in July , but the French declined to engage the British ships . The ship accompanied the British squadron to Newport , Rhode Island as it attempted to lift the Franco - American siege , but " Vigilant " was badly damaged when a storm interrupted the planned battle on 13 August . Despite the damage , she supported British troops on 29 – 30 August as they pursued the retreating Americans who had abandoned the siege after the French ships sailed to Boston for repairs . A few days later , on 4 September , the ship collided with the sloop - of - war " Raven " during the British raid on New London , Connecticut and had her bow stove in by the other ship . " Vigilant " was quickly repaired in New York and participated in the attack on Little Egg Harbor River in October . At the beginning of December , the ship sailed from New York to Savannah , Georgia to assist in the attack on that city . Despite dismounting her main armament , the ship had to keep one or more pumps running continuously during the voyage to prevent her from sinking . She arrived at Savannah on 28 December , after the British had secured the city . Her nine - pounder guns were ordered removed when she was reclassified as an 20 - gun armed transport on 22 December . Throughout 1779 , " Vigilant " supported British operations along the coasts of Georgia and South Carolina , despite running aground several times . Lacking substantial repairs during this time , the ship ' s condition deteriorated until her crew refused to take her to sea from Beaufort , South Carolina on 28 February 1780 to support the planned siege of Charleston . She was then surveyed and condemned as " utterly unfit for sea " and decommissioned on 9 April . Her crew and armament were loaded aboard the transport " Margaret & Martha " and taken to Charleston where they were transferred to the transport " Margery " , which had been purchased and renamed to serve as " Vigilant " s replacement . The ship was burnt at Beaufort sometime later that year .