Middlebrook encampment The Middlebrook encampment was a seasonal encampment of the Continental Army during the American War for Independence near Middle Brook in Bridgewater Township , New Jersey ( between Martinsville and Bound Brook ) in 1777 and again in 1778 – 79 . The site includes part of the ridge of the First Watchung Mountain . Its position provided a natural fortress not only protecting the Continental Army but also overlooking the plains towards New Brunswick , where the British forces were stationed in 1777 . The strategic strength of the position contributed ultimately to the success of the Continental Army . Today , a portion of the encampment site , known as the Washington Camp Ground , is preserved as a National Historic site . The first Middlebrook encampment ( 1777 ) . During the winter of 1776 – 77 , Washington rested the Continental Army initially at the encampment near Morristown , New Jersey . After his outpost garrison at Bound Brook was surprised and routed during the Battle of Bound Brook in April 1777 , Washington moved the encampment closer to Bound Brook to the Middlebrook encampment on May 28 and stayed there until July 2 . A total of 8 , 298 soldiers were housed in the encampment , but 2 , 660 of them were sick or disabled , unable to fight . In contrast , the British maintained a force of about 17 , 000 near New Brunswick , New Jersey . From the heights of the Watchung mountains Washington could monitor and counteract British movements . When General Howe decided to move against Philadelphia , concern over the threat by the Continental Army made him choose the safer sea route instead of the faster land route . This led to a significant delay in operations for the British and disrupted plans to help General Burgoyne in northern New York . On June 30 , Howe moved his troops to Staten Island in preparation for his Philadelphia campaign , and two days later Washington left Middlebrook and moved the army to Pompton Plains . First flag : June 1777 . Tradition holds that it was at the Middlebrook encampment that the first official flag of the United States was unfurled , after a law to adopt a national flag had been passed by Congress on June 14 , 1777 . This event is commemorated annually since 1889 on July 4 with a changing of the flag , a reading of the Declaration of Independence , and the delivery of an historical address at the Washington Camp Ground . Also , by special order of Congress , a Thirteen Star Flag is flown 24 hours a day at the Washington Camp Ground . The second Middlebrook encampment ( 1778 – 79 ) . Washington used the Middlebrook grounds again in the Winter of 1778 – 9 . He brought about 8 – 10 , 000 troops to the camp site by November 30 , 1778 . Soldiers constructed cabins from logs covered with clay similar as they had done at Morristown . Washington himself rented the Wallace House ( now converted to a museum ) in Somerville for four months and paid Wallace $ 1 , 000 . General von Steuben lived at the Staats House in South Bound Brook . General Henry Knox lived at the Jacobus Vanderveer House in Pluckemin with the Continental Army Artillery known as the Pluckemin Artillery Park . The main body of the much larger British army was at New York . The camp was closed on June 3 , 1779 when Washington led his army to Highlands , New York . Today . The Washington Camp Ground , on Middlebrook Road in Bridgewater Township , just north of Route 22 , was dedicated a historic site by local citizens in 1889 , and entered the National Register of Historic Places July 3 , 1975 . The site is owned and preserved by the Washington Camp Ground Association , which also organizes the annual July 4 program at the site . The program includes a public reading of the complete Declaration of Independence , which has been read at the site each July 4 for about 120 years . Various other sites related to the encampment , in Bridgewater and surrounding towns , are accessible to the public . These include Washington Rock State Park , an observation site on top of the Watchung mountain ridge , in Green Brook , Washington Valley Park in Bridgewater ( nearby , but separate from , the Washington Camp Ground ) , the Wallace House in Somerville , and the Staats House in South Bound Brook . A sign commemorating the encampment also stands in a now - developed area , at the corner of Chimney Rock and Gilbride Roads in Bridgewater .