[1] In December 1776, Philippe Charles Tronson de Coudray and a group of French officers left for America on the Amphitrite.

[2] Anxious to get on with their journey, Lieutenant du Plessis and Philippe Hubert Preudhomme de Borre went aboard the Mercure.

[4] At the Battle of Germantown on 4 October 1777, the American offensive stalled when Lieutenant Colonel Thomas Musgrave and 120 British soldiers of the 40th Foot stoutly defended the Chew House.

To fellow aide John Laurens, du Plessis suggested the idea of fetching hay from the nearby barn and using it to ignite the structure.

[6] Later that month, George Washington sent du Plessis to Fort Mercer to take command of the garrison's artillery and also to oversee its defenses.

Du Plessis immediately constructed a new wall that bisected the old works, effectively abandoning a large part of the fort in order to concentrate the defenses in a smaller area.

Du Plessis later related to François-Jean de Chastellux that Stuart's overbearing tone inspired the defenders to greater resistance.

[12] That night, amid the horrible groans of the wounded Hessians, du Plessis heard a voice in English pleading for help.

Though some Americans taunted the wounded Hessian with his "no quarter" message, du Plessis managed to calm the men down and get medical treatment for his adversary.

Gilbert Motier, marquis de La Fayette led about 300 Americans against the British rear guard in the Battle of Gloucester.

[15] After receiving a letter from Washington praising du Plessis' good work at Brandywine, Germantown, and Fort Mercer, the Continental Congress voted to promote the Frenchman to lieutenant colonel.

[4] Historian Robert K. Wright Jr. asserted that du Plessis was "instrumental" in familiarizing American officers with the writings of Jacques Antoine Hippolyte, Comte de Guibert at Valley Forge during the 1777–1778 winter.

This work stressed that foot soldiers be trained to fight as both line and light infantry, and to use both columns and linear formations on the battlefield.

Guibert was also influenced by artillery theorist Jean-Baptiste Vaquette de Gribeauval who urged gunners to group their guns into massed batteries and to mainly direct their fire on the enemy infantry.

Although Friedrich Wilhelm von Steuben played a more significant role in introducing professionalism among American officers, du Plessis was nevertheless highly respected as an instructor.

[16] At the Battle of Monmouth on 28 June 1778, Charles Lee led the 5,000-man American advance guard to attack Sir Henry Clinton's British army.

[18] Washington arrived with the army's main body to find Lee's advance guard in full retreat in the face of Clinton's counterattack.

[19] At about the same time, Washington sent William Woodford's 3rd Virginia Brigade and four cannons under du Plessis to block any British attempt to turn his right flank.

Soon afterward, the American commander encountered Lieutenant Colonel David Rhea who told him about high ground on the south flank.

[20] Around 3:00 PM Greene reached on Comb's Hill to find it protected on three sides by a swampy stream and overlooking the British left flank.

[21] On 5 November 1778, Congress granted du Plessis leave to resign from the Continental Army and ordered that a letter be prepared testifying to his "zeal, bravery and good conduct".

Historian Francis B. Heitman related no more about his service with the American army and did not list him in his separate roll of French officers.

The new soldiers quickly made common cause with local revolutionary elements and told the men of the Port-au-Prince Regiment that their commander had been executing false orders.