The siege of Arcot (September-October 1751) was the first major success in the career of Clive of India, and saw him capture and then defend the capital of the Carnatic in an attempt to lift the pressure on a British force being besieged in Trichinopoly.
By the summer of 1751 the French, under Governor Joseph Dupleix were in a dominant position in southern India. They had played a major part in the success of Chanda Sahib, one claimant to the title of Nawab of the Carnatic, and their candidate also held the senior post of Nizam of Hyderabad, officially the Mughal Emperor's viceroy in the south of India. The British were officially at peace with France, and so could only act against them as allies of an Indian leader. The only remaining rival to the French was Mohammed Ali, the son of a previous Nawab of the Carnatic, but he was besieged in Trichinopoly.
A British army had been sent to cooperate with Mohammed Ali's field army, but had been defeated at Volkondah (19-20 July 1751) and forced to retreat to Trichinopoly. Robert Clive (Clive of India), had been with this army, but had returned to Fort St. David. He then played a part in getting s convoy into Trichinopoly, but again avoided becoming besieged.
Clive now suggested an audacious move that he hoped would force Chanda Sahib to divert some of his troops from the siege. Arcot, the capital of the Carnatic, was only lightly defended. Clive believed that a small force would be able to capture Chanda Sahib's capital and hold it against any counterattack.
Governor Saunders recognised the merit of Clive's plan. Most British troops were trapped in Trichinopoly, but Saunders was able to provide Clive with 200 Europeans, 300 Sepoys and three field guns. This force left Madras on 6 September, and by 11 September Clive was able to halt only ten miles from Arcot.
In 1751 Arcot was a city of around 100,000 people. The city was unfortified although it did contain an almost ruined fort. The city was defended by a garrison of around 1,000 Indian troops, half of them cavalry. The garrison included some artillery, and when Clive attacked two or three French artillerymen who were training the Indian gunners.
After his brief halt Clive continued on towards Arcot on 11 September, marching through a thunderstorm. News of Clive's approach reached the garrison, and they fled without firing a shot. Clive was able to occupy the abandoned fort, and immediately began to fortify it.
Joseph Dupleix wanted Chanda Sahib to ignore the fall of Arcot, and instead focus on the rapid capture of Trichinopoly. Chanda Sahib didn't take this advice, and instead sent 4,000 of his best men, commanded by his son Raju Sahib, to retake his capital. Dupleix provides 100 French soldiers, while other levies raised Raju Sahib's force to 10,000 men. This army occupied the indefensible town of 4 October and began the siege of the fort.
On 5 October Clive led a sortie against the besieging army. This was a mistake, costing him 33 killed and wounded amongst his 200 European troops. Two weeks later Raju Sahib's siege train arrived, and on 4 November two 18 pounder guns arrived from Pondicherry. A practical breach was made in the north-west walls by 10 November, and Raju Sahib summoned Clive to surrender. Clive refused, but Raju Sahib delayed his assault for another two weeks, hoping that a lack of supplies would force Clive to surrender.
Raju Sahib was eventually forced to order an assault by events elsewhere. A first British attempt to get reinforcements to Clive had failed when the relief force was defeated at Tirupatur on 5 November. Governor Saunders had been more successful at recruiting allies, and had succeeded in winning over the Marathas. A force of 6,000 Marathas under Murari Rao was now approaching, and so Raju Sahib decided to launch his assault on the fort on the morning of 25 November. He planned a two-pronged assault. The main assault, led by elephants with iron battering plates on their heads, would attack the north-western breach, while a second force would attempt to cross the wet ditch at the south-west on rafts.
By this point Clive only had 80 Europeans and 120 Sepoys left, but on 24 November a deserter (or possibly a spy) warned him of the impending attack, giving him time to prepare. The few guns were moved into place facing the breach, while a large number of muskets were pre-loaded to allow the defenders to maintain a high rate of fire.
The more serious of the attacks came at the breach. In an attack that lasted for an hour Clive's small garrison fired 12,000 musket shots (sixty each, or one per minute for the entire duration of the assault), as well as manning the few field guns. Raju Sahib's men suffered around 400 dead and wounded. Amongst the dead was the leader of the assault. Clive's men only lost six dead and wounded.
On the day after the failed assault Raju Sahib lifted the siege and moved away to Vellure. Part of his army disappeared after the setback at Arcot, but he retained the 4,000 men he had brought with him and 300 Frenchmen. He inflicted a defeat on Clive's Maratha allies at Vellure, but Clive won another victory at Arni (3 December 1751), then captured Conjeeveram (16-18 December 1751). After that he put a garrison in Arcot, and returned to Fort St. David.
The successful defence of Arcot had a massive impact on the British position in southern India, restoring the prestige their earlier setbacks had lost. Dupleix began to lose allies, while Trichinopoly still held out. Fighting continued around that city for another two years, but the siege of Arcot marked the beginning of a period of French decline, and the beginnings of the rise of the British.