According to historian Don Sharp, he was not truly appreciated by the politicians of the day. His life story is complicated, and much controversy revolved around him not getting paid in full for his years of work designing and building those three buildings, possibly the most famous buildings in Louisiana. He left disheartened for Pensacola, FL, where he died a few years later.
"It is an important story," Sharp said. "for New Orleans, for Louisiana and the nation. Guillemard was a Frenchman by birth, but a loyal soldier in the Spanish Army. His work as a surveyor and architect was essential to early New Orleans, especially his work on designing and building the Cabildo, St. Louis Cathedral and the Presbytere."
Sharp believes that Guillemard died in Pensacola in 1808, most probably of yellow fever, and is buried in St. Michael's Cemetery there. He has contacted cemetery officials and reports that they are in the midst of a thorough examination of the gravesites using new technology so that an accurate map can be generated of the graves.
Here is a short interview with Don Sharp recorded on September 13, 2023, in which he explains his research and his conclusions about the last few years of Guillemard's life, his final resting place, and his impact on Louisiana history, especially regarding his highly accurate and detailed survey of Mandeville in its infancy.