During the War of Independence his early training at the French military college at Caen enabled him to render effective service to General Benjamin Lincoln in 1778-1779, to Count d'Estaing (1779), to General Lincoln in the defence of Charleston and afterwards to General Horatio Gates.
To capture this British garrison, later increased to 6000 men, the co-operation of about 10,000 men (mostly New England militia) under Major-General John Sullivan, and a French fleet carrying 4000 French regulars under Count D'Estaing, was planned in the summer of 1778.
Count D'Estaing hastily re-embarked his troops and sailed out to meet Howe.
On the loth, D'Estaing returned to the port with his fleet badly crippled, and only to announce that he should sail to Boston to refit.
In the same year he was despatched with a fleet to watch the movements of the Count d'Estaing, and in July 1779 fought an indecisive engagement with him off Grenada.
4, 1777); in March 1778 he was placed in command in Rhode Island, and in the following summer plans were made for his co-operation with the French fleet under Count d'Estaing in an attack on Newport, which came to nothing.
An unsuccessful attempt was made to drive them out in 1778 by the Americans assisted by the French admiral d'Estaing and a French corps.
In September 1 779 he was besieged by Lincoln in conjunction with a French naval and military force under Admiral d'Estaing, but successfully repelled an assault (October 9), and Lincoln again fell back to Charleston.
On the coast of America the news of the approach of d'Estaing compelled the British commanders to evacuate Philadelphia on the 18th of June.
Howe then concentrated his force of nine small line-of-battle ships at Sandy Hook on the 29th of June, and on the 11 th of July he learnt that d'Estaing was approaching.
The French admiral, who had anchored above Newport, R.I., came to sea to meet him, but both fleets were scattered by storms. D'Estaing sailed to Boston on the 21st of August.
On the 4th of November d'Estaing sailed for the West Indies, on the very day that Commodore William Hotham was despatched from New York to reinforce the British fleet in those waters.
D'Estaing, who followed Hotham closely, was beaten off in two feeble attacks on Barrington at the Cul-de-Sac of Santa Lucia on the 15th of December.
But in June, while Byron had gone to Antigua to guard the trade convoy on its way home, d'Estaing first captured St Vincent, and then on the 4th of July Grenada.
D'Estaing, after co-operating unsuccessfully with the Americans in an attack on Savannah, in September also returned to Europe.
Though superior in force, D'Estaing would not attack the English in the roadstead, but set sail to attack Savannah.