Charles Henri Hector, Count of Estaing

Portrait by Jean-Pierre Franque

After a lengthy journey, the fleet of the comte d'Aché, carrying the expeditionary forces whose land commander was the count de Lally, arrived off British-occupied Cuddalore in southern India on 28 April 1758.[10] Lally disembarked his troops, established a blockade around the town, and then traveled to Pondicherry to organize the delivery of siege equipment. On 4 May French forces occupied the town and partially blockaded Fort St. David.[11] The siege equipment was delayed in its arrival, but the garrison was eventually compelled to surrender after 17 days of siege operations. D'Estaing commanded Lally's left, overseeing the approaches and placing of batteries.[12] He continued to serve under Lally in his campaigns against the British in southern India. He opposed Lally's decision to lift the siege of Tanjore (the only one in Lally's war council to do so) following the British seizure of Karikal. When Lally began to besiege Madras in December 1758, d'Estaing's division was positioned in the center of the French line. When the British made a sortie against that sector, d'Estaing advanced alone to reconnoiter their movements. He was surrounded by British troops, unhorsed, and twice wounded by bayonet before surrendering.[13]

D'Estaing was taken into Madras, where he was confined by the order of Governor George Pigot. Pigot offered to release him on parole, but d'Estaing refused, preferring instead to be exchanged so that he could resume fighting.[14] The arrival of a British fleet off Madras in February 1759 convinced d'Estaing to accept the offer of parole, which was conditioned on his not fighting against the British in the East Indies.[15] In May 1759 he sailed for Île-de-France (present-day Mauritius).[16]

While d'Estaing was at Île-de-France, word arrived of a prisoner exchange agreement between France and Britain. D'Estaing, however, was excluded from this agreement because he had been paroled before its date. While requests were forwarded to India to negotiate his inclusion in the cartel, d'Estaing decided to enter the service of the French East India Company, leading a naval expedition to gather resources for Île-de-France. D'Estaing thought he would finesse his parole status by declaring himself to be a "spectator" in case the force came into conflict with the British or their allies, and permitted his second in command to lead such operations.[17]

In command of a two-vessel company fleet (the 50-gun Condé and the frigate l'Expédition), d'Estaing sailed for the Persian Gulf in September 1759. From an Arab convoy captured at the end of the month, he learnt of a British ship at Muscat. In a daring commando operation, 50 of Condé's men entered the well-fortified harbour and boarded the ship, taking it without resistance. In their haste to depart, the men cut lines necessary for towing the ship, and alarm was eventually raised in the port. A swarm of small boats was driven off by precision fire from Condé, allowing a new line to be attached to the prize so that she could be towed out of the harbour.[18] D'Estaing then destroyed the British factory at Bandar-Abbas,[19] before sailing for Sumatra. While en route he detached his accumulated prize ships, sending them to Île-de-France. D'Estaing's success was notable: in three months he had acquired significant prizes at the expense of only five casualties (28 men died of smallpox).[20]

After a slow crossing (retarded by calms and contrary winds), d'Estaing's fleet reached the coast of Sumatra in early February 1760. There he captured the British factory at Natal, which he eventually turned over to the Dutch. He sailed for the British outpost at Tappanooly (present-day Tapanuli in the Indonesian Province of North Sumatra). Its commander put up stiff resistance, fleeing into the hills when it was clear the French would be victorious. D'Estaing consequently decided to destroy the fortifications rather than hunt down the British. He next sailed for Padang, a major Dutch settlement, where he supplemented his forces with local recruits and resupplied.

He sailed for Bencoolen (now Bengkulu, the capital of the Indonesian province of Bengkulu), the main British settlement on Sumatra. The town was defended by Fort Marlborough and a garrison of 500 Europeans and local sepoys, with the potential to raise over 1,000 additional Malay militia. Although these forces were alerted to the French arrival by a ship that d'Estaing chased into the harbour, the first broadside directed at the fort panicked its defenders, who fled into the surrounding jungle. D'Estaing spent a day in pursuit of some of these troops. He used Fort Marlborough as a base to subdue the remaining lesser British settlements on the west side of Sumatra. He returned to Île-de-France ten months after his departure.

Ordered back to France, d'Estaing boarded a westbound company ship. Just off the French coast the ship was captured by British patrols. He was imprisoned at Plymouth, charged with violating his parole, before being granted limited freedom from a house in London. He was able to successfully defend himself against the charges, and was allowed to return to France. Upon his arrival, d'Estaing was commissioned as field marshal, the reward for his service in the East Indies.

In the early months of 1762 France made preparations for a major expedition against Portuguese territories in South America. Promoted to lieutenant general of the army on July 25, 1762, d'Estaing was also given the rank of chef d'escadre (rear admiral) in the French Navy in recognition for his exploits, a rank lesser than that he held in the army. In order to clarify his command role in the expedition, the king formally removed him from the army and gave him the rank of lieutenant general in the navy. The expedition was called off when preliminary peace terms were agreed.

In 1764 King Louis appointed d'Estaing governor general of the French Leeward Islands, a post he held until 1766. Based principally in Saint-Domingue (present-day Haiti), he recruited French colonists known as Acadians to settle there. They had been deported from the French colony of Acadia in present-day Canada by the British during the war, as they had refused to take loyalty oaths to Britain. These efforts were largely unsuccessful, as many Acadian immigrants died of tropical disease. Others sought to resettle elsewhere because of the hot climate and poor land.

D'Estaing returned to France in 1767. At this time he had to deal with the formal separation from his wife, which they had agreed to in writing in 1756, before his departure for India. The division of their properties was somewhat contentious, leading to court proceedings and appeals that ultimately failed to divide their estates.

In 1772 d'Estaing was appointed naval inspector and governor at Brest, the country's principal Atlantic naval station. In 1777 he was promoted to vice admiral of the Asian and American seas (vice-amiral des mers d'Asie et d'Amérique).

In cooperation with the American generals, d'Estaing planned an attack on Newport, Rhode Island, preparatory to which he compelled the British to destroy some war vessels that were in the harbor. Before the concerted attack could take place, he put to sea against the British fleet, which was under Admiral Howe. Owing to a violent storm, which arose suddenly and compelled the two fleets to separate before engaging in battle, many of his vessels were so shattered that he found it necessary to put into Boston for repairs. He sailed for the West Indies on 4 November.[21]

He arrived in the West Indies in December 1778, shortly after the British began operations to capture St. Lucia. He sailed in an attempt to relieve the place, but he was defeated in both land and naval efforts to prevent its capture.

In June 1779, with his fleet reinforced by arrival of ten ships of the line commanded by Comte de Grasse, he took advantage of the temporary absence of his British opponent, Admiral John Byron, to take action against nearby British possessions. He first detached forces that captured St. Vincent on 18 June, and then set sail with his entire fleet, intending to capture Barbados. When he was unable to make progress against the prevailing westerly trade winds, he turned his sights on Grenada. On 2 July he arrived off the island, which his forces took by storm two days later.

Admiral Byron had been alerted to the capture of St. Vincent, and was sailing with a force to retake it when he learned that d'Estaing was at Grenada. He changed course, making all sail for Grenada, and arrived there early on 6 July. Although d'Estaing had been alerted to Byron's progress, and his fleet outnumbered Byron's, he still scrambled to embark soldiers and sail away from the island. Byron, unaware that d'Estaing had been reinforced, ordered a general chase, which resulted in a somewhat disorganized battle.[22] D'Estaing refused to press his numerical advantage, and both fleets ended up retiring to their bases for repairs. In August, d'Estaing sailed for Savannah, Georgia, to join forces with the Americans who wanted to recapture the British-held city.

An October 1779 map by Antoine O'Connor, d'Estaing's chief engineer, of the coastline to the east of the Savannah colony, including Bonaventure Plantation[23]

The siege consisted of a joint Franco-American attempt to retake Savannah from 16 September 1779 to 18 October 1779, with d'Estaing in overall command of the combined forces. After weeks of fruitless bombardment, on 9 October 1779, a major assault against the British siege works failed. During the attack, d'Estaing was twice wounded. When the assault failed, d'Estaing lifted the siege. British forces remained in control of coastal Georgia until they withdrew near the end of the war.