How did the Continental Army fare in the early battles of the war?
The American Continental Army lost every battle for nearly year after its win at the Battles of Lexington and Concord.
On April 19, 1775 when British troops marched through Lexington on their way to Concord to capture the ammunition stored there, the rag-tag American Militia, known as the Minutemen, attacked the British troops in a fashion Britain had not before encountered and so were able to prevail. But from that point onward, the Continental Army lost pretty much every battle and every skirmish until December 26, 1776.
Gen. George Washington had a very small number of regular soldiers at his command for most of the Revolution. He had to rely upon the various colonies to provide militia to fill out his army. These militia showed up virtually untrained and unprepared for the rigors of war.
America's first "defeat" came at Bunker Hill June 1775. The well-trained and well-armed British regulars simply out lasted the under-gunned Americans. The British did win the battle, took the hill, but took no prisoners and lost 10 men to every 1 the Americans lost.
After that Washington moved south to New York where he hoped to assemble and train an army to fight the British. Gen. Howe had other ideas and together with his brother, Admiral Howe, they chased Washington entirely out of New York. Had it not been for a heavy fog, Washington's army would certainly have been eliminated and Washington probably captured.
Washington's first true victory came at Trenton on Christmas when he attack the Hessian Troops gathered there on Christmas Day. The Hessians could not imagine that anyone would attack of Christmas! After that, with American morale rejuvenated, Washington starting winning.