 General Howe hoped that capturing Philadelphia , the rebel capital , would end the war at a stroke . Cornwallis was given command of the army 's light infantry in the campaign , which got underway when the army disembarked at Head of Elk ( now Elkton , Maryland ) on 25 August 1777 . Advance units of Cornwallis 's division were involved in the Battle of Cooch 's Bridge on 3 September , as the army began its march northward . At the Battle of Brandywine on 11 September , Howe and Cornwallis led the flanking movement that ultimately forced the Americans from their position . Cornwallis also played an important role in the Battle of Germantown on 4 October , bringing up reinforcements late in the battle . When Howe sought to gain control over the Delaware River approaches to Philadelphia , Cornwallis was sent into New Jersey in November to secure Fort Mercer after a failed Hessian assault . The Americans abandoned the fort as his column approached . General Howe then sent Cornwallis to probe Washington 's position at White Marsh in December ; these movements resulted in a series of inconclusive skirmishes . When the army entered winter quarters in Philadelphia , Cornwallis took his long @-@ delayed leave , sailing for England on 13 December . In addition to spending several months with his devoted wife , he informed the government of affairs in the colonies and visited the families of his colleagues . He sailed from England on 21 April 1778 , and arrived in Philadelphia in early June , after a crossing that was much more pleasant than his first in 1776 . 
