The expanding British Empire

In 1763, as the Wentworth mansion was being built, England was the  big winner of the recent Seven Years War In Europe (what we call the French and Indian War). The king had gobbled up new territory in Canada, West Africa, India, Florida, and the West Indies. Britain was the new and undisputed master of the seas and an emerging power in science and technology. Her colonies across the globe were booming and the people of Portsmouth were still loyal subjects of the English King.

In order to define and develop her expanding colonies, Britain needed accurate maps and charts and pictures. Enter mapmaker Joseph F.W Des Barres, a fascinating but largely forgotten character. French or Swiss by birth, Des Barres was an ambitious military surveyor and cartographer who was hired to chart British North America, especially Nova Scotia and the capital city of Halifax. With a wife on one continent and a mistress on the other, Des Barres reportedly fathered 17 children. (Ironically, after being kicked out of Portsmouth, Loyalist John Wentworth would become royal governor of the Nova Scotia province where he built a costly stone mansion that still stands in Halifax.)

 Mapping colonial harbors was especially important to the British Admiralty and Board of Trade. Pervious maps had been out of scale, badly drawn, and unreliable. Using the latest technology, Des Barres created the first truly accurate maps of the complex bays, creeks, islands, and shoals of the rocky North Atlantic coastline. His trained crew worked from small boats, often weathering harsh conditions in the Canadian Maritimes.

Des Barres, used a method of triangulation to create overlapping triangles on the shore to map the coastline. His team included hydrographers who measured depths of water along the coast and in the harbors.

Atlantic Neptune and Mr. Holland

F.W. Des Barres' extraordinary maps, charts, and illustrations were assembled in four volumes entitled The Atlantic Neptune . They were published in London during and after the American Revolution. And while the work is often attributed to Des Barres, it was actually a Dutch cartographer named Samuel Holland who created the first images of Portsmouth. As Surveyor General of North America in 1764 Holland began mapping CapeBreton, St. John's, and PrinceEdwardIslands. He used innovative surveying techniques and high-tech equipment including an astronomical clock and a refracting telescope 

Moving south from Quebec to Portsmouth in 1770, Holland found a prosperous seaport exporting timber and dried fish with an active trade to the West Indies. A number of homes were more elegant than those he had seen in the evolving port at Halifax. Gov. John Wentworth, while living on Pleasant Street, was helping to establish Dartmouth College and building his summer mansion near Wolfeboro. Seeing a rare opportunity to expand the state westward, Wentworth tried to obtain funding to have Holland survey and map more of New Hampshire, but was unsuccessful. Holland also proposed creating a province along the Maine coast between New Hampshire and Nova Scotia to be known as "New Ireland." That too failed.

Holland's team first mapped From Cape Ann to the KennebecRiver, along Casco Bay, and the AndroscogginRiver , then along the SalmonFalls and MerrimacRivers. Gov. Wentworth, who was officially "Surveyor of the King's Woods" even accompanied Holland on his mapping journeys and helped support his work on the Piscataqua.  But as Holland's crew moved through Massachusetts, Connecticut, and Rhode Island, the drums of the coming war beat louder.

The powder raid on FortWilliam and Mary in New Castle, the battles at Lexington and Concord, and the expulsion of Gov Wentworth put a whole new spin on the valuable maps Holland had been creating. They now had military significance in a territorial war. Fearful for his safety, Samuel Holland abandoned his survey in New York and returned to England as the American Revolution erupted. By the time the Atlantic Neptune was fully published in London by J.F.W. Des Barres, Portsmouth had become a key port in the new United States of America.

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