Scarce and attractive plan of Louisbourg fortress

Dessine par J. Seibel Bombardier / Grave par [Georg Joseph] Contgen Graveur de la Cour et de l'Universite de Mayence / [L. Therbu, publisher], LE PLAN de LOUISBOURG dans l'Isle royale au Canada. Frankfurt, ca. 1789-91.
Engraved map on laid paper, 14"h x 9 ¼"w plus good margins, uncolored

A scarce retrospective plan depicting the strategic fortress of Louisbourg on Cape Breton Island, site of one of the most significant British victories of the French and Indian War.

After the 1713 Treaty of Utrecht left them in control of Cape Breton Island, the French began constructing a huge fortress at Louisbourg. The site provided a large, sheltered and easily-defended harbor, in close proximity to the vital shipping lanes of the Gulf of St. Lawrence and the American East Coast. Prior to the establishment of Halifax in 1749, this strategic location rendered Louisburg the dominant naval base in northeastern North America. In spite of these advantages, or perhaps because of them, the fortress was captured twice, first in 1745 by a Colonial force under Massachusetts Governor Shirley and again in 1758 by a massive British force led by Admiral Boscawen and Lord Amherst. British control of Louisbourg greatly magnified the difficulties faced by the French in reinforcing and supplying New France, and directly contributed to the capture of Quebec the following year.

This fine and boldly-engraved plan depicts Louisbourg as it appeared before its capture in 1758. The layout of the town and the surrounding fortress is shown quite clearly, and a legend below the image identifies 27 locations of significance, including some civilian establishments but emphasizing the massive fortifications. Not shown are the sheltered, heavily fortified harbor to the north and west, or the British landing place at Gaberus Bay further south along the coast.

The plan was issued in Les plans de la guerre de sept ans, an atlas illustrating key locales and battles of the Seven Years’ War, apparently issued in parts between 1789-91. The plans primarily depict European subjects but include three other plates with North American content, namely the battles at Forts Oswego, Ticonderoga and William Henry. All but this plan of Louisbourg and one other plate credit Therbu as the mapmaker, and all bear the engraver’s imprint of Georg Joseph Contgen. I have found no background on Seibel or Therbu, but the engraver’s imprint informs us that Contgen was an engraver to the court and university at Mainz, Germany.

Phillips, Atlases, #3979.10. Sellers & Van Ee, Maps and Charts of North America and the West Indies, #339 (incorrectly suggesting a date of 1758).