His first posting was to Brest but in February 1764 he was sent to Martinique, in the West Indies, where he was put in charge of building the new Fort Bourbon and this task occupied him until June 1772.

In 1787 with Tenon he visited the Royal Naval Hospital, Stonehouse and they were impressed by the revolutionary "pavilion" design and recommended it to the French government.

On the outbreak of the Revolution in 1789, he resigned his appointment as intendant des eaux et fontaines and retired to a small estate which he possessed at Blois.

His name is one of the 72 names inscribed on the Eiffel Tower.In 1784, his memoir Recherches théoriques et expérimentales sur la force de torsion et sur l'élasticité des fils de metal[4] (Theoretical research and experimentation on torsion and the elasticity of metal wire) appeared.

His general result is: the moment of the torque is, for wires of the same metal, proportional to the torsional angle, the fourth power of the diameter and the inverse of the length of the wire.In 1785, Coulomb presented his first three reports on electricity and magnetism: Il résulte donc de ces trois essais, que l'action répulsive que les deux balles électrifées de la même nature d'électricité exercent l'une sur l'autre, suit la raison inverse du carré des distances.

Translation: It follows therefore from these three tests, that the repulsive force that the two balls — [which were] electrified with the same kind of electricity — exert on each other, follows the inverse proportion of the square of the distance.Four subsequent reports were published in the following years: Coulomb explained the laws of attraction and repulsion between electric charges and magnetic poles, although he did not find any relationship between the two phenomena.

He completed the most comprehensive study of friction undertaken in the eighteenth century and was named by Duncan Dowson as one of the 23 "Men of Tribology".

[14] This work introduced what is now known as the wedge theory of earth pressure and established several key principles for analyzing the stability of soil masses, including: Coulomb's analysis went beyond the practical engineering solutions of his time by systematically applying principles of statics and mechanics to problems of soil stability.

His methods, although refined by later researchers, laid the groundwork for modern soil mechanics and retaining wall design, and remain relevant in geotechnical engineering.