When Louis XV reviewed the French Royal Army after the end of the disastrous Seven Years' War, he insisted all regiments be equipped and organised the same way.

These reforms were pioneered by the late Maurice, Duc de Saxe (Duke of Saxony), who had served in the Seven Years' War with great distinction.

[1] Each company of Grenadiers would consist of: 1 x Captain, 1 x Second Captain, 1 x First Lieutenant, 1 x Second Lieutenant, 6 x Sub-Lieutenants (Port Drapeau), 1 x Sergeant Majors, 1 x Caporal-Fourrier, 4 x Sergeants, 8 x Corporals, 1 x Cadet Genleman, 1 x Frater (padre), 84 x Grenadiers, 2 x Drummers or other instruments, totalling 180 men, including the officers.

The 2nd and 4th battalions of that regiment then separated to form the new Régiment d'Armagnac, named after the historic province, today part of the departments of Gers, Landes, and Lot-et-Garonne.

[5] Towards the end of 1779, Continental forces were eager to re-take Savannah, Georgia, which had become a launching point for British raids in the area.

As Jean-Baptiste Charles, Comte d'Estaing arrived with his squadron near the Georgia coast, a small French ground force joined them.

As the squadron neared the city, it was required to stay away due to the naval batteries and possible heavy artillery, while the rest of the troops were ordered to some 5 miles away and marched to join their American allies.

On 9 October they were again attacked, but after a fierce battle, Lieutenants Molard and Nairne de Stanlay were killed, the French were repulsed and the siege called off entirely.

[5] After their terrible expedition to Georgia, in 1780, part of the regiment boarded ships of the squadron of Lieutenant Général des Armées Navales Luc du Bouëxic, Comte de Guichen, which had orders to immediately set sail for the West Indies.

[5] In 1782, a detachment embarked in the beginning of the year with Armand, Comte de Kersaint's squadron as part of his effort to recapture the Dutch colonies of Demerara (1 February) and Essequibo (5 December).

[5] During the campaign in the south, the main part of the regiment contributed to the French Invasion of Saint Christophe, where among those cited for gallantry, included Colonel de Livarot, Lieutenant Colonel Feydcau, Captains Tarragon and de Grillières, Lieutenants Dumont, des Ecures, Charpy, and Descressonnières.

[5][10] After capturing the Prince of Wales Fort, the expedition re-embarked bound for York Factory, the capital of Hudson's Bay Company.

[5][10] After making a name for itself during the wars in the Colonies, the Armagnac regiment returned to France with an overwhelming sense of pride.

On 21 July 1783, they landed in Lorient, and thereafter marched to Thionville to re-train, re-equip and recruit back to full establishment.

When the 21 February 1779 ordnance was issued, the regiment had been deployed oversees, and therefore wasn't able to gain its new uniforms until the return to France in 1783.

After the retreat of the Prussians, the whole of the 1st Battalion passed to the Army of the North Armée du Nord and contributed to the decisive Siege of Lille.

Under the new constitution, all royalist lineages and attachments were lost, though the 1st Battalion was able to escape being amalgamated as the regiment's supposed successor, 11éme Demi-Brigade, only existed on paper.

[13] The 2nd Battalion also contributed to General Adam Philippe, Comte de Custine's Army of the Rhine Armée du Rhin and its conquest of the Palatinate and was garrisoned in Mainz after this successful campaign.

[5] The battalion arrived in Nancy on 4 August after being transferred from the Rhine, and joined the Army of the West (Armée du l'Oest) under François Séverin Marceau.

[16] As the Regiment d'Armagnac was from a historic province with strong ties to the monarchy it was able to maintain its own distinctive colonel's colours.