Siege of Pondicherry ( 1778 ) The Siege of Pondicherry was the first military action on the Indian subcontinent following the declaration of war between Great Britain and France in the American War of Independence . A British force besieged the French - controlled port of Puducherry in August 1778 , which capitulated after ten weeks of siege . Background . Following the American victory at Saratoga in October 1777 , France decided to enter the American War of Independence as an ally to the United States . Word first reached the French India n colony of Puducherry in July 1778 that France and Britain had recalled their ambassadors , a sign that war was imminent . The British colonies had already received orders to seize the French possessions in India and begun military preparations . French defenses . Pondicherry was the capital of French India and the largest of France ' s possessions on the subcontinent . The British would capture all of the other possessions without resistance in 1778 ; only Pondicherry was actively defended . The French governor , General Guillaume de Bellecombe , had at his disposal about 700 French troops and 400 sepoy s ( local Indian troops ) , and a city whose fortifications were in some disrepair . Pondicherry , as was the case with a number of other European colonial outposts in India , changed hands due to military action several times in the colonial period . Attempts to significantly improve its defences after the last round of battles in the Seven Years ' War were frustrated by political infighting in the French colonial administration . In 1778 the outer works of the city were largely incomplete , with significant elements unfinished and parts of the city exposed to direct attack . Bellecombe immediately set about improving the defences , working as quickly as possible in anticipation of British movements . Key gates were blocked , stockade s and gun batteries were constructed along the shore , and anything that might give cover to the British on their advance on the defences was removed or destroyed . Bellecombe also received additional troops before the British arrived . The garrison from Karikal ( which the British occupied on 10 August ) add about 100 sepoys to the defence , and some of Pondicherry ' s inhabitants also took up arms . A small French navy was assembled to counteract the small British navy . Admiral Tronjoli took command of the 64 - gun ship of the line " Le Brillant " , and the rest of the fleet consisted of the frigate " La Pourvoyeuse " and three smaller ships , " La Sartine " , " Le Lauriston " , and " Le Brisson " . The siege . Preliminaries . The British colonial administration in Madras placed General Hector Munro in command of an army of nearly 20 , 000 men , which began arriving within a few miles of Pondicherry on 8 August . By 20 August the full army had arrived , the city was surrounded , and siege operations began . The first noteworthy exchange between the forces was a naval encounter . Admiral Edward Vernon ' s fleet also consisted of five ships , carrying slightly less firepower than the French fleet . Vernon commanded the 60 - gun ship of the line , and was assisted by , , , and the East India Company ' s ship " Valentine " . In a largely inconsequential two - hour engagement in which Tronjoli was wounded , the French fleet drove Vernon away on 10 August . On 14 August French ships spotted two unknown sails ; they were transport ships of the British East India Company . Their captains , apparently unaware of the hostilities , sailed before Pondicherry with British flags flying . Two of the French fleet , " Pourvoyeuse " and " Sartine " lazily gave chase . The British merchant ships escaped , but " Sartine " was captured when she strayed too close to the British squadron on 25 August . The loss of parity between the navies was partially made up by the arrival at Pondicherry of the 26 - gun frigate " Elizabeth " , another private ship that had been pressed into service in the French fleet . On 20 August , the British fleet , now six ships , appeared again . The French fleet , although it had been augmented by " Elizabeth " , was forced to leave " Le Brisson " in the harbour due to damage sustained in the first engagement , and was thus at a disadvantage . The next day , Tronjoli sailed the rest of the fleet south . Sources disagree on whether or not battle was offered or attempted on either side , but apparently no battle took place , and Tronjoli continued south . Bellecombe was surprised and dismayed to learn on 2 September that Tronjoli had sailed for Île de France , leaving " Elizabeth " and " La Pourvoyeuse " behind . The British troops were not noticeably active in their siege operations until September . Bellecombe used the remaining time to further strengthen the defences , constructing more dikes and iron - cladding the powder magazine . He also repeatedly had to stop the ineffective fire of cannon at the distant British positions . Siege operations . On the night of 1 September the British advanced a force of about 300 as cover for engineers to begin siege operations . Two positions were identified for attack ; the northwest bastion , and the southernmost bastion . Batteries were established to cover this work , and a third battery was placed to the southwest on 3 September that was positioned to enfilade the French defences . Bellecombe ' s response was to send out a few hundred men to feint an attack on the southern battery . This drew nearly 3 , 000 British troops within reach of the French guns , which inflicted significant damage with only a single French death . The British siege operation proceeded throughout September , often under heavy fire . British batteries moved progressively closer to the walls , inflicting heavy damage within the city . The hospital had to be evacuated , and the powder magazine ( a particular target of the British guns ) was also emptied . On 19 September a British cannonball killed the commander of the French artillery . By 24 September breaches were beginning to show in the bastions under attack , and by 6 October the British trenches had reached the inner ditches , with additional gun batteries doing significant damage along the entire French works . On 25 September the French attempted a nighttime sortie to destroy the southern battery . The effort was abandoned when secrecy was lost ( a sentry was disarmed but not killed , so he was able to raise the alarm ) and when the company lost its way . A second sortie on 4 October was a little more successful . The southwest gun battery was reached while its crew was asleep ; the guns were spiked ( albeit poorly enough that they were soon back in service ) , and some of the crew were slaughtered . Bellecombe also received a minor injury after a musket ball struck him on 4 October , but was able to continue leading the defence . Siege ends . Between 6 and 13 October the British siege operations continued , but heavy rains hampered them . The British succeeded in draining the northern ditch , which the French unsuccessfully attempted again to flood . On 14 October the walls of the two bastions the British had targeted lay in ruins , and preparations began for an assault . Bellecombe was also running out of ammunition . After holding a war council on 15 October , he sent a truce flag to Munro the next day . He signed the terms of capitulation on 18 October . Aftermath . The French force of less than 1 , 500 had withstood a siege of nearly eighty days by a British force that numbered 20 , 000 . The defenders ' losses were high : more than 300 French and nearly 150 sepoy casualties , along with more than 200 civilian casualties . The British suffered more than 900 casualties . The French defenders were allowed to march out with full colours , and were eventually returned to France . Britain followed up the victory by seizing France ' s other Indian colonies , contributing to the outbreak of the of Second Mysore War .