There were three principal contractors responsible for the building of Louisbourg. In turn, they were: Michel-Philippe Isabeau (1717-1724), Francois Ganet (1725-1735) and David-Bernard Muiron (1736-1745). I here intend to briefly deal with the third of them, Muiron.
Muiron was to win his first contract at Louisbourg during May of 1737. He had arrived at Louisbourg the previous year, an experienced 53 year old French contractor. He came, as the DCB points out, with three matters in mind, not all of which, I imagine were immediately disclosed to the locals: to develop a sawmill at a nearby creek; to establish a tannery; and to size up the fortification work which was then being done by Francois Ganet and which was shortly to be up for bid, once again.
Muiron had experience in dealing with government and in the supervision of large construction projects back in France; the building of roads and bridges was a specialty of his. He apparently had dealings with Ganet's ex-partner, Gratien d'Arrigrand back in France (see the page on Ganet); and, it seems clear now, that Muiron was tipped off that there were easy pickings to be had at Louisbourg. It would appear that Arrigrand had previously picked up a concession from the government for the establishment and the running of a sawmill; it needed, however, an on-site operator such as Muiron (Muiron did not pursue it). The tannery business might have been an opportunity which Arrigrand pointed to; in any event, Muiron set up a tannery. Further, Muiron set up a workshop on the north side of Louisbourg harbour powered by a water mill. On the whole Muiron seem to be an organizer and a very industrious man. His big coup, though, was to outbid Ganet on the fortification contract in 1737 (underbid him by 20%). Thus it was that Muiron became a bit of a tycoon at Louisbourg and was very active during the years 1737-1745.