Lear Beyer, a member of the Revolutionary Rye 250 Committee, gave an illuminating slide presentation last month at the Rye library, titled “Prelude to the Revolution in a New York Border Town.”
Among his exhibits was a fascinating map, labeled “Town of Rye 1779,” which showed locations of numerous Rye homesteads, identified by the names of their owners. As Beyer described in detail, members of some families were all Loyalists, while others were all Patriots, but often, large families were divided in their allegiances. Occasionally, cousins and even brothers fought on opposite sides.
When I looked at the map more carefully, I noticed that it was very similar to a map included in Charles W. Baird’s “History of Rye,” which is labeled “The Town of Rye in 1779 by Robert Erskine, FRS., Geographer to Army of U.S.” That comparison led me to fascinating facts about Erskine’s valuable map work for George Washington during the Revolutionary War, especially in Westchester County.
According to a biography of Erskine, he was born in Scotland in 1735 and received university training in mathematics and engineering. Due to his achievements as an engineer, he was elected a Fellow of the Royal Society (FRS). Emigrating in 1771, he settled in New Jersey, where he was employed as manager of an ironworks company.
In 1776, Gen. Washington petitioned Congress to allow him to establish a surveying and mapping department that would be attached to his headquarters. “The want of accurate Maps of the Country … has been of great disadvantage to me. I have in vain endeavoured to procure them and have been obliged to makeshift with such Sketches as I could trace out from my own Observations and that of the Gentlemen around me … If gentlemen of known character and probity could be employed in making maps from actual survey of the roads, of the rivers and bridges and fords over them, and of the mountains, and the passes through them, it would be of the greatest advantage.”
Washington was a good judge of surveying talent, as his early professional career was spent as a surveyor in Virginia, where he became adept at drawing as well as using maps for various purposes. Accounts of his experience during the French and Indian War also refer to his reliance on maps tactically and strategically.
It appears that Erskine’s reputation as an experienced surveyor and cartographer as well as leader of a New Jersey Patriot militia won him an introduction to George Washington in 1777. After his meeting with Erskine, Washington received approval from Congress to appoint him to the post of geographer and surveyor general of the Continental Army. Erskine also received the rank of colonel, reported directly to Washington, and supervised a “corps of surveyors.”
Several maps Erskine made of Rye, Harrison, and White Plains in 1779 document road networks and terrain as well as the names of property owners. Knowing whose farm was near a certain road might allow Washington to seek shelter or intelligence from known Patriots or anticipate where British forces might find local support.
A detailed article in the Journal of the American Revolution reported that “in September 1778 Erskine spent six weeks at the Continental Army’s camp at White Plains and was later with General Washington at his headquarters in Pawling, New York … It is clear that Erskine was not only devoting himself full-time to the drawing of maps but was also traveling with Washington.”
In December 1779, Washington decided to build his winter encampment at Morristown, N.J., and instructed Erskine to accurately survey the roads in front and rear of the camp as speedily as possible.
During 1780, Erskine’s department shrank to a few surveyors, apparently because Congress had not authorized increases in their pay. As a result of spending more of his time surveying in all kinds of weather, Erskine became seriously ill and died on Oct. 2, 1780, at the age of 45.
There is an official “History of the Department of the Geographer to the Army, 1777–1783,” which provides a detailed account of Erskine’s pivotal role in professionalizing military intelligence for the Continental Army. The publication catalogs the output of the department under Erskine’s leadership. By the time of his death, he had overseen the production of over 275 numbered maps.
