According to the National Park Service: "On the morning of July 3, a force of about 600 French and 100 Indians approached the fort. After the French took up positions in the woods, Washington withdrew his men to the entrenchments. Rain fell throughout the day, flooding the marshy ground. Both sides suffered casualties, but the British losses were greater than French and Indian losses.
"The fighting continued sporadically until about 8 p.m. Then Capt. Louis Coulon de Villiers, commander of the French force... requested a truce to discuss the surrender of Washington's command. Near midnight, after several hours of negotiation, the terms were reduced to writing and signed by Washington and Mackay. The British were allowed to withdraw with the honors of war, retaining their baggage and weapons, but having to surrender their swivel guns. The British troops left Fort Necessity for Wills Creek on the morning of July 4, From there they marched back to Virginia. The French burned Fort Necessity and afterwards returned to Fort Duquesne."
Things were a lot different 21 exactly years later. One the same day in July, in Cambridge, Massachusetts, the middle-aged Washington assumed command of the colonial forces fighting British regulars -- and not even yet for independence.
From "Washington Takes Charge" by Joseph J. Ellis in the January 2005 Smithsonian magazine: "The siege of Boston from June 1775 to March 1776 marked Washington’s debut as commander in chief. Here, for the first time, he encountered the logistical challenges he would face during the ensuing years of the war. He met many of the men who would comprise his general staff for the duration. And here he demonstrated both the strategic instincts and the leadership skills that would sustain him, and sometimes lead him astray, until the glorious end.
"The story of the siege can be told in one sentence: Washington’s makeshift army kept more than 10,000 British troops bottled up in the city for more than nine months, at which point the British sailed away to Halifax. Less a battle than a marathon staring match, the conflict exposed the anomalous political circumstance created by the Continental Congress, which was prepared to initiate war a full year before it was ready to declare American independence.
"Although Washington subsequently claimed that he knew by the early fall of 1775 that King George III was determined to pursue a military rather than political solution to the imperial crisis, he went along with the prevalent fiction that the British garrison in Boston contained 'Ministerial Troops,' meaning that they did not represent the king’s wishes so much as those of evil and misguided ministers."