In April, 1775, there were approximately 3,000 British regulars in Boston commanded by General Thomas Gage, who was also the military governor of Massachusetts. Boston had been occupied since 1768 and the military force there had been recently augmented to enforce what the colonists called the "Intolerable Acts" which had been passed by the British Parliament to punish Massachusetts for acts of protest that included the "Boston Tea Party".
Gage was generally sympathetic to the colonials and tried to separate his role as Military Governor from that of a General of occupying forces as much as possible.
The colonists had been forming its own militia groups since the 17th century. The British made full use of these militia units in the French and Indian War in the 1750s and 1760s.
But now Gage received an order from the Earl of Dartmouth on April 14th to disarm these militia, now simply called rebels. There was known to be a stash of hidden weapons in Concord. He was also ordered to arrest the burgeoning rebel leaders -- especially Samuel Adams and John Hancock.
On the morning of April 18th, Gage sent out a small mounted patrol to intercept any messengers who may have been out and about on horseback. But this patrol didn't behave as British patrols at this time normally did and started asking questions about the whereabouts of Adams and Hancock.
All this accomplished was to alarm the population and increase the state of preparedness of the rebel colonists.
In particular, the militia at Lexington began to muster early that evening.
On the afternoon of the 18th, Gage ordered Lieutenant Colonel Francis Smith to secretly take a detachment of troops to Concord and "seize and destroy all military stores". Gage attempted discretion and decided not to issue written orders to arrest Hancock and Adams for fear of sparking a general uprising.
The rebels, in the meantime, had learned of Gage's instructions even before Gage did himself from their own sources in London. They also learned of Gage's plan.
Between 9:00pm and 10:00pm on the evening of the 18th, Joseph Warren (one of the rebel leaders) told William Dawes and Paul Revere that the British redcoats were about to embark on boats from Boston to Cambridge and thence to Lexington and Concord.
Dawes was not overly worried about the weapons cache in Concord, but he was concerned that the militia in Lexington might be caught by surprise.
Revere rode to Lexington, avoided a British patrol and warned practically every house on the way that the "Regulars are coming" (not the "British are coming" -- as they all still considered themselves to be Englishmen at this time).
The British advance guard under Major John Pitcaim entered Lexington at sunrise on April 19th, 1775. 77 Lexington militiamen under Captain John Parker (almost 1/3 of these men were in one way or another related to Parker) emerged from Buckman Tavern to meet them.
Parker was aware that his little band was outmatched and was not prepared to risk his men. He was purported to have said: "Stand your ground; Don't fire unless fired upon, but if they mean to have a war, let it begin here."
A British officer, probably Pitcaim, rode forward to demand that the gathering crowd lay down their arms and disperse. Parker, in fact did order his men to stand down. Pitcaim ordered his men to hold their fire.
Parker, suffering from Tuberculosis, could not be heard with all the shouting that was now going on, but his men did begin to disperse (without laying down their arms).
Suddenly, from an unknown source, a shot rang out. Nobody knows for sure to this day who that person was, but it probably was not from any of the assembled men on the Lexington Green.
The British then charged forward with fixed bayonets. 8 militiamen were killed and 10 were wounded in the melee that followed. Only 1 British redcoat was killed.
The main force of the British arrived under Lieutenant Colonel Smith and restored order to the now blood-lusted British troops under Pitcaim.
They now formed up and headed toward Concord - some 700 strong.
The militia at Concord, under command of Colonel James Barnett were alerted to the events at Lexington and decided to proceed with caution, conceding Concord to the British but forming up on the hills to the north near the North Bridge. Other militiamen started to join them from the surrounding countryside.
Smith and Putcaim did find some military supplies in the form of three 24 lb cannon, which they disabled. They also found some musket balls and threw them into the river (later recovered by the militiamen).
At this time, the North Bridge was guarded by a small detachment of British, but a force of more than 400 "minutemen" now descended upon them.
Colonel Barnett ordered his men to hold their fire as the British retreated across the Bridge.
Just like at Lexington, a shot rang out. But this one was from a British regular who was probably panicked and was just trying to fire a warning shot.
Now both sides fired volleys into each other.
The regulars at the bridge found themselves outmaneuvered and outnumbered. They retreated back in panic toward the British main force.
In the meantime, the British in Concord finished their task of disabling the cannon. They stopped for lunch before resuming their march back to Boston, giving the minutemen and militia time to gather on the road back.
The British force was harassed all the way back to Boston, taking many casualties as the militia fired at them from behind trees and fences. Occasionally, groups of several hundred militia would stand and fire volleys at them, but mostly, the militia used ambush tactics.
Colonists even fired at the British from their own households.
The British reached safety in Boston and Cambridge but now found themselves surrounded by an army of over 15,000 aroused colonialists.
The siege of Boston and the American Revolution had begun.
