Washington and his army already lost one battle with the British to protect Philadelphia. So, they went to Valley Forge, and they camped there for several months. Everyone was very cold, with barely any clothes and shoes. Some soldiers had the full uniform on. Many died of diseases like typhoid. Food became scarce, and soldiers left without permisson. Later a man came to help train the army. His name was Baron Von Steuben. The army became proficent and a mature army. Washington marched his army to Monmouth. On June 19, 1778, the British abondned Philadelphia, and marched back to New York City. Washington and his army fought the British after 6 months of being at Valley Forge and making allies with the French. It ended in a draw, but Washington's army claimed Philadelphia.
Primary Source: www.americanrevolution.org/vlyfrgeltrs.html
This is the website that we gathered most of our information: www.ushistory.org