Col. James Barrett - Battle of Concord

My ancestor is Jame's sister Lydia who married Samuel Farrar. I am looking for the names of books detailing the Battle of Concord that I might request on inter library loan. I understand that Col. Barrett gave the order for the colonial forces to advance on the British, but not to fire unless fired upon. He is said to have said, "If they mean to have a war, let it begin here." They were fired on, and a war did result. Correct me if I am mistaken.