On his way back to France in 1760, he fell, accidentally, into the hands of the English. On the ground of having broken his parole, he was thrown into prison at Portsmouth but as the charge could not be substantiated, he was soon afterwards released. In 1763, he was named lieutenant-general in the French navy, and, in 1777, vice-admiral. One year later, he left Toulon in command of a fleet of twelve ships of the line and fourteen frigates with the intention of assisting the American colonies against Great Britain. He sailed on April 13, and, between the 11th and the 22nd of July, blockaded Lord Howe at Sandy Hook, the entrance to New York harbor, but did not venture to attack him, because his ships could not clear the bay's bar, although his force was superior numerically.
In cooperation with the American generals, he 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 English fleet, under Lord Howe, when 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 then sailed for the West Indies on November 4. After a feeble attempt to retake Santa Lucia from Admiral Barrington, he captured St Vincent and Grenada.
On July 6 1779 he fought a drawn battle with Admiral Byron, who retired to St Christopher. Though superior in force, D'Estaing would not attack the English in the roadstead but set sail to attack Savannah. All his attempts, as well as those of the Americans, against the town were repulsed with heavy loss, and he was finally compelled to retire.
He returned to France in 1780, but he fell into disfavour at the court. Three years later, however, he was placed at the head of the Franco-Spanish fleet assembled before Cádiz, but the peace was signed and no operations took place.
From that time, his chief attention was devoted to politics. He was first made a grandee of Spain and, in 1787, he was elected to the Assembly of Notables. When the French Revolution broke out, he favoured the new ideas. In 1789, he was appointed to the National Guard at Versailles and, in 1792, he was chosen admiral by the National Assembly. Though in favour of national reform, he remained loyal to the royal family, and, in the trial of Marie Antoinette in 1793, bore testimony in her favour. On this account, and because of certain friendly letters which had passed between him and the queen, he was himself brought to trial, charged with being a reactionary. He was sent to the guillotine on 28 April, 1794. D'Estaing died without issue, and despite sharing a name, former French President Valéry Giscard d'Estaing is no relation.
In his moments of leisure, he wrote a poem, Le Rêve (1755), a tragedy Les Thermopyles (1789) and a book on the colonies.