Invasion of Dominica The Invasion of Dominica ( 7 September 1778 ) was a successful French invasion of the island of Dominica in the British West Indies , during the American War of Independence . The action took place before British authorities in the Caribbean were aware that France had entered the war as an ally of the United States of America . The French governor in the West Indies , François Claude Amour , marquis de Bouillé was notified on 17 August that France was at war , and organized the invasion , infiltrating spies to rally sympathetic French - speaking Dominican support . Early on 7 September 1778 , French forces landed on the southeastern coast of the island . They rapidly took over some of the island ' s defences , and eventually gained control of the high ground overlooking the island capital , Roseau . Lieutenant Governor William Stuart then surrendered the remaining forces . Dominica remained in French hands until the end of the war , when it was returned to British control . Background . Following the pivotal Battles of Saratoga in October 1777 and the ensuing surrender of British General John Burgoyne ' s army , France decided to openly enter the American War of Independence as an ally of the young United States of America . France ' s objectives in entering the war included the recovery of territories that had been lost to Britain in the Seven Years ' War . One key territory that was of particular interest was the West Indies island of Dominica , which lay between French - held Martinique and Guadeloupe , and had been captured by Britain in 1761 . Recapture of the island would improve communication among the islands , and deny the use of Dominican ports to privateers who preyed on French shipping . On Dominica , Governor Thomas Shirley had been concerned about the island ' s security since the war began in 1775 . Operating against instructions from colonial authorities in London to minimize expenses for defence , he had pushed forward the improvement of a fort at Cachacrou and other sites . This work was incomplete when Shirley took leave in June 1778 , sailing for England . Command was left with Lieutenant Governor William Stuart , and work to improve the defences was still incomplete in August 1778 , when François Claude Amour , marquis de Bouillé , the governor of the French West Indies , received word that war had been declared . Prelude . The French frigate " Concorde " reached Martinique on August 17 with orders from Paris to take Dominica at the earliest opportunity , and de Bouillé made immediate plans for such an operation . He had maintained contacts in the Dominican population , which had remained largely French during the years of British administration . As a result he had an accurate picture of the condition of the Dominican defences , and knew that the island ' s garrison numbered fewer than " fifty soldiers fit for duty " . He was also concerned with the whereabouts of the British Leeward Islands fleet of Admiral Samuel Barrington , which was significantly more powerful than his own . Unbeknownst to de Bouillé , Barrington , who had only recently assumed his post , was under orders to retain most of his fleet at Barbados until further instructions were received . The British regular forces on the island , which in total numbered about 100 , were distributed amongst defences in the capital Roseau , the hills that overlooked it , and at Cachacrou . De Bouillé carefully maintained a facade of peace in his dealings with Dominican authorities while he began preparing his forces on Martinique . On 2 September he and Lieutenant Governor Stuart signed an agreement that formally prohibited privateering crews to plunder . The next day de Bouillé sent one of his officers to Dominica to see whether a Royal Navy frigate was still anchored in Prince Rupert ' s Bay ( near present - day Portsmouth ) . Stuart , suspicious of the man , had him questioned and then released . On 5 September de Bouillé was informed that the frigate had sailed for Barbados . He immediately moved to launch his invasion . Some Frenchmen ( some British sources suggest they were French soldiers infiltrated onto the island ) gained entry to the battery at Cachacrou that evening , plied its garrison with drink , and poured sand into the touchhole s of the fort ' s cannons , temporarily rendering them useless . De Bouillé had in fact infiltrated some agents onto the island who had convinced some of the local French - speaking militia to abandon their duties when called up . Invasion . After sunset on 6 September , 1 , 800 French troops and 1 , 000 volunteers departed Martinique aboard the frigates " Tourterelle " , " Diligente " , and " Amphitrite " , the corvette " Étourdie " , and a flotilla of smaller vessels . ( Sources describing the action give significantly varying numbers for the size of the French force . The numbers here are from de Bouillé ' s report of the action ; some British sources claim his force numbered as much as 4 , 500 . ) The first point of attack was the battery at Cachacrou , where the British garrison , befuddled by drink and with inoperative cannons , was overcome without significant resistance around dawn on 7 September . Two of the 48th Regiment ' s soldiers were driven over the ramparts and fell to their deaths . After securing the battery the French fired cannons and sent signal rockets skyward to signal their allies . These actions also alerted Lieutenant Governor Stuart at Roseau , and the alarm was immediately raised . Many of the French Dominican militia failed to muster , as arranged . About 100 militia ended up mustering for duty , and were deployed among Roseau ' s defences . The French proceeded to land more troops between Cachacrou and Roseau , with the objective of gaining the high ground above the capital . The main force of 1 , 400 men was landed about south of Roseau near Pointe Michel , with heavy fire from the hill batteries resulting in 40 casualties . De Bouillé landed with another 600 at Loubiere , between Pointe Michel and Roseau , while another 500 landed north of Roseau , and the fleet ' s frigates moved to bombard Roseau ' s defences . The French briefly captured the coastal fort at Loubiere , but were three times driven out by fire from above . They ended up withdrawing until forces were able to reach and capture the hill batteries . By noon , the French occupied the high ground above the capital , and Lieutenant Governor Stuart realised the situation was hopeless . Negotiations followed , and Stuart and de Bouillé signed the terms of capitulation at about 3 : 00 pm . The proceedings were interrupted by one of the French frigates , whose captain , apparently unaware of the proceedings , fired on Fort Young , where the British flag was still flying . The two commanders rushed to the fort to prevent further exchanges of gunfire before they completed the agreement . The French then formally took control of Roseau . The British regulars were made prisoners of war , and the militia were released to return home . De Bouillé , who was interested in keeping on good terms with the population , did not allow his troops to plunder the town . Instead , he levied a fee of £4 , 400 on the island ' s population that was distributed among his men . Aftermath . De Bouillé in official correspondence claimed the French suffered no casualties . Lieutenant Governor Stuart reported that the French appeared to be concealing the casualties that occurred during the invasion . De Bouillé left a garrison of 800 ( 700 French regulars and 100 free black militia ) on the island , turned its command over to the Marquis de Duchilleau , and returned to Martinique . News of Dominica ' s fall was received with surprise in London . Considering a single ship of the line might have prevented the attack , Admiral Barrington was widely blamed for the loss , and criticised for adhering too closely to his orders . The orders and reinforcements whose late arrival had held Admiral Barrington at Barbados were to launch an attack on St . Lucia , which took place in December 1778 . These events were the first in a series of military actions resulting in the change of control of Caribbean islands during the war , in which de Bouillé was often involved . Thomas Shirley was appointed Governor of the Leeward Islands in 1781 , and was taken prisoner by de Bouillé in the 1782 British surrender of Saint Kitts . Dominica remained in French hands until 1784 , when , much to de Bouillé ' s annoyance , it was returned to British control under the terms of the 1783 Treaty of Paris . The fact that the French had supplied natives and mixed - blood locals with arms during the invasion caused problems for the British . These local forces , which were previously somewhat pacific , resisted British attempts to expand their holdings on the island , leading to expanded conflict in 1785 .