On May 10th, 1775, two very important things happened.
(1) Ethan Allen and the Green Mountain Boys captured Fort Ticonderoga in New York from British soldiers, along with its cannons. And Benedict Arnold helped - a lot! In 1775, Benedict Arnold had not yet become a traitor.
The Green Mountain Boys took no lives.
(2) The Second Continental Congress met in Philadelphia and elected George Washington the commanding general of the Continental Army (colonial forces).