YORKTOWN CAMPAIGN– Manuscript map, "No 1 Carte générale de l'Isle de New York et des Environs... No 2. Reconnoissance Geometrique des Ouvrages du Nord de L'isle de New York faite les 21 et 22 Juillet 1781. Soutenue par un Corps de 5000 hommes aux ordres des Generaux Washington et Comte de Rochambeau detaché de l'Armeé Combineé Campeé a Philisburg.” n.p., c. 1781-1782.
One sheet, 630 x 402mm, on thick laid paper, accomplished in ink and watercolor (several spots of light soiling, pinhole at fold intersection).
An important manuscript map of New York City prepared by cartographers attached to Rochambeau’s forces during the Yorktown Campaign. A superb example of the cartography produced by the staff of Rochambeau's expeditionary force sent to assist the Continental Army in 1780 which would prove critical in securing the surrender of Cornwallis's Army at Yorktown in 1781. The present map depicts the primary objective at the start of the 1781 campaign: the city of New York. Held by the British since September 1776 after driving out Washington's army at the Battle of Long Island, it remained the North American headquarters for His Majesty's arms in America. Driving the British from this all-important post would have spelled an immediate end to the war – securing American independence.
The sheet bears two distinct maps. The first and larger map, offers an overall view of New York Harbor, from the tip of Sandy Hook in the south to present-day Riverdale in the north, and from the Passaic River in the west to Jamaica Bay in the east. Certain areas of the map, especially in Westchester, bear a high degree of detail – reflecting the French cartographers's familiarity with the area. Conversely, British-held Manhattan and eastern Long Island are more vague. Although familiar places such as Coney Island (which was only a sandbar at the time) are lacking, the mapmakers did include one very important detail, the narrow sandbar between the Narrows and Sandy Hook, that was passable only at high tide. A fleet attempting to take New York by sea would be obliged to enter the lower harbor single file. A small complement of British warships could easily bring the advance to a disastrous end for the French. (Hell Gate, the alternate entrance to New York's vast harbor, was even more treacherous.) With British forces controlling the waters, the only possible scenario required an attack against the imposing fortifications at the very north of Manhattan. The second map, an estimate positioned across the top of the sheet, details the immediate vicinity of King's Bridge. Spanning Spuyten Duyvil Creek, it was the only land crossing to Manhattan, and for that reason, the British concentrated an array of fortifications to guard it – features depicted in great detail on this map.
The present map was based on observations taken during a major demonstration by Franco-American forces along the Harlem River. From 21 to 23 July 1781, French and American troops maneuvered in and around King's Bridge, Morrisania and Throggs Neck, allowing Washington and Rochambeau an opportunity to reconnoiter personally the British defenses around northern Manhattan. Jean-Alexandre Berthier, one of the most skilled cartographers working with Rochambeau's army, recalled in his journal for 22 July, "Generals Washington and Rochambeau, with their respective engineers aides, and myself, made a reconnaissance of all the English works along the Harlem River between King's Bridge [see previous] and Morrisania." (Rice, The American Campaigns of Rochambeau's Army, 1:252-253) Crèvecœur recalled that after "inspecting the points in front of the army," Washington and Rochambeau "crossed the Harlem River to examine the opposite bank There they were shelled without result, whereupon they came back across the river and continued along their original route in order to reconnoiter the island as far down as the city of New York." During this whole time, British frigates kept a steady fire "on the generals without consequence." (Rice, 1:36) When they reached Morrisania, they were surprised by "about 20 Loyalists," against which Washington ordered eight of his dragoons to charge and short skirmish ensued resulting in a rout of the Loyalists. According to Berthier, "The generals watched this little skirmish, which lasted five minutes, at very close range." (Ibid, 1:253)
Due to the many hands involved in producing maps for the French army, attribution is challenging. Like most of the maps produced by Rochambeau, very few were ever signed (this one included). The map at top (No. 2) covers an area depicted in a series of maps of the King's Bridge [see previous] area, including examples at the Library of Congress (Rochambeau Map Nos. 28 and 31); as well as several other versions in private and French institutional collections. The lower map (No. 1) covers most of the area covered in Number 21 in the Rochambeau Map Collection at the Library of Congress. (Neither map on the present sheet appears to have been traced directly from the examples found at the Library of Congress.) Of the possible authors, the brothers Louis-Alexandre and Charles-Louis Berthier were most prominent among the cartographers with Rochambeau's force. Although they were not attached to the staff assigned to produce maps (that task was handled by the Royal Corps of Engineers), Rochambeau was quick to recognize their talent for mapmaking and set them to work. Louis-Alexandre Berthier's work is well represented in the collections of the Library of Congress and other major repositories. In addition to the Berthier Brothers, Rochambeau employed other mapmakers including members of the Royal Corps of Engineers, under the command of Colonel Desandroüins, as well as Mathieu Dumas, one of his aides-de-camp, and Baron von Closen of the Royal Deux-Pons Regiment. (Ibid, 2:116-117)
If any doubts remained as to the futility of a general attack on Manhattan, they were probably quashed here. Washington already understood that such a gambit was highly risky even under the best of conditions. And the plan agreed to at Wethersfield proposed operations against New York with the stated objective of relieving pressure against Lafayette in Virginia who was then sparring with a larger British force under the command of Lord Cornwallis. To that end, two attempts were made to probe the British defenses of northern Manhattan: an aborted raid headed by Benjamin Lincoln in early July, and a much larger demonstration by 5,000 men along the shores of the Harlem River (which helped inform the present map). However, on 14 August 1781 Washington and Rochambeau learned that a large French fleet, commanded by the Compte de Grasse would be arriving soon in Chesapeake Bay. Based on this intelligence, the generals decided to risk an enormous gamble. While maintaining a ruse that convinced British General James Clinton in New York that the French and Americans were planning siege operations against the city (and refused Cornwallis' requests for reinforcements as a result), Washington and Rochambeau began marching most of their forces to the south. Clinton did not detect the ruse until 2 September, when reports of Continental troops marching triumphantly through Philadelphia arrived. By then it was too late to send reinforcements to Virginia. The French navy had bottled up Chesapeake Bay. Cornwallis, who had fortified Yorktown on the James River was now trapped. On the morning of 28 September, formal siege operations against Yorktown began. After less than a month of bombardment as well as key advances against the British lines by the Continental Army, the British surrendered their forces on 20 October 1781. The battle proved to be the last major engagement of the American War of Independence. Provenance: François-Jean de Beauvoir, Marquis de Chastellux (1734-1788) – by descent to the consignor.