Louis M. Thibault, architect, engineer and surveyor, studied at the Acad?mie Royale d'Architecture in Paris in 1775, where he appears to have been a brilliant student. According to Louis M.J.O. Degrandpr?* he subsequently trained as an engineer officer in the Corps des Ponts et Chauss?es de France. In 1781 he joined a Swiss mercenary regiment led by Count Charles D. De Meuron*, who financed his further studies in military engineering. His regiment was employed by the Dutch East India Company for the defence of the Cape, arriving in January 1783. Thibault, who held the rank of lieutenant of engineers, left the regiment in 1785 and entered the Company's service with the same rank. On 2 April 1786 he married Elisabeth van Schoor, with whom he had three daughters, and in 1788 was promoted to captain.
In 1786 Thibault was appointed inspector of the Company's buildings, under Captain Sebastiaan W. van de Graaff*. The next year he was in addition appointed head of the new military academy for artillery cadets. With van de Graaff and Lieutenant D.M. Barbier* he surveyed and mapped False Bay and Hout Bay in 1787. He appears to have been employed also as an architect by Governor C.J. van de Graaff* until the latter's departure in 1791, and by the time of the first British occupation of the Cape in 1795 he had not only built up a successful practice as an architect, but was chief military engineer of the Dutch East India Company. Though he lost his government post when the British annexed the Cape in 1795, he was appointed in 1799 as architect of military works. Soon after Sir George Yonge arrived as governor in December 1799 he was furthermore appointed to make a survey of government buildings that required repair. He was also admitted as a government land surveyor, probably early in the year 1800.
When the Cape was handed over to the Batavian republic in 1803 Thibault lost his post again, but that same year was appointed inspector-general of public works by commissioner-general J.A. de Mist. During the next few years, as the first formally trained architect at the Cape, he designed most new public buildings and supervised their construction and repair. His architectural style had little in common with the local style, now known as Cape Dutch, and was tempered by local taste and by available craftmanship. The buildings that are attributed to him include Papenboom, Newlands, the residence of Dirk G. van Reenen (1787-1788); Lodge De Goede Hoop in Cape Town for the Freemasons, of which he was a member (1803); the guard house to the Company gardens (1804); the Drostdy at Graaff-Reinet (1804-1805); the customs house in the Buitenkant (1814); and the slave lodge at the upper end of Adderley Street (1814-1815).
After the second British occupation of the Cape in January 1806 Thibault again briefly lost his post, but was re-appointed as inspector-general of public works in April. The next year he was (again) permitted to practice as a surveyor and in 1811 succeeded Jan W. Wernich* as government surveyor. From that time he became concerned more with surveying than with architecture. Among others he surveyed part of the road between Cape Town and Simonstown and drew up plans for the Westervoord bridge and another bridge at Dieprivier along the route.
Thibault owned two measuring rods with a length of six Rhynland feet each. After his death these were bought by surveyor M. Ruysch*. These rods appear to have been the first, and at the time the only, standards of length available in the colony to control the length of the local unit of land measure, called the Rhynland foot. A commission led by Thomas Maclear* compared these rods with British standards in 1858 and found the length of the land unit to be 1.033 British Imperial feet (314.85mm). The commission renamed the unit the Cape foot. It remained in use until replaced by the metre in the nineteen-sixties.