At Cambridge Washington had used a flag with thirteen stripes of red and white, and the red and white cross of the British flag in the corner; in 1777 Congress adopted as the national flag one with the stripes but having, instead of the British cross, thirteen stars to represent the thirteen colonies. As we said, the Americans were unable to prevent the British from landing in New York. Then the patriots were defeated in the battle of Long Island and Washington was forced to retreat. Pursued through New Jersey, he crossed the river into Pennsylvania, with about three thousand ragged, hungry, discouraged soldiers. It was now winter and it was supposed that the troops would go into winter quarters. But Washington did not wish to give up the year’s campaign without striking one successful blow. By a sudden march the day after Christmas, he surprised and captured a force of one thousand Hessians at Trenton and then he defeated an English force at Princeton. These victories inspired hope and the patriots began the campaign of 1777 with renewed courage. But it was a year of reverses. The patriots were defeated at Brandywine in September and at Germantown in October and went into winter quarters at Valley Forge in December in a pitiable condition. They lacked clothing, food, military stores. The campaign in the north was more successful. At Saratoga General Gates won a signal victory and Burgoyne was forced to surrender his army. It was this victory which led the French to declare in favor of the colonists. There was formed a conspiracy to depose Washington and to put at the head of the army General Gates who had won the victory of the campaign. Congress, however, supported Washington and collected men and supplies for a new campaign. The army was drilled in the winter of 1778 by Baron von Steuben, a Prussian officer who had served under Frederic the Great. In 1778 the British evacuated Philadelphia and Washington attacked them at Monmouth. Here he had a clash with General Charles Lee; his temper, usually under control, rose at what he considered General Lee’s failure to perform his duty. The little army marched north and encamped near White Plains. In this vicinity it remained during the year. During the campaign of 1779 also, Washington remained in the Highlands of the Hudson on the defensive. The next year came French aid. That same year the plot of General Arnold to surrender West Point to the English was discovered from papers in the possession of a captured spy. This spy, the brave young General André, paid the penalty with his life; the traitor Arnold escaped to the British. In 1781 brilliant victories were won at the south by General Greene, General Morgan and by Marion, called “the Swamp Fox.” That same year Washington, aided by the French troops, invested Lord Cornwallis’s men at Yorktown, and forced them to surrender.