By 1775, the British Prime Minister, Lord North, had had enough. He and Parliament had made conciliatory gestures to the troublesome North American colonies twice already. The first by repealing the Stamp Act in 1766 and the second by repealing the Townsend Acts in 1770. He was not going to do the same with the Coercive Acts. In January 1775, North ordered General Thomas Gage, the Governor General of Massachusetts and commander of the occupying army in Boston, to arrest the nucleus of the shadow government, the Massachusetts Provincial Council, who controlled most of the colony outside of Boston. The Massachusetts Provincial Council met in the crossroads town of Concord and was instrumental in raising rebel “minuteman companies” of militia (because they said they were ready to fight at a minute’s notice) to oppose the British. In February 1775, Parliament and King George III officially declared the Massachusetts Colony in a State of Rebellion.
In April 1775, Gage correctly believed that the radical patriot group Sons of Liberty were behind most of the overt acts of rebellion. On 14 April, Gage finally received Lord North’s specific instructions. On 15 April 1775, Gage received intelligence that two of the Sons of Liberty’s most important leaders, Sam Adams and John Hancock, were in Lexington, 12 miles away. The Massachusetts’s Provincial Council had just adjourned until May and Adams had orders to go to Philadelphia immediately. Furthermore, loyalist spies also reported there were cannon, gunpowder, and muskets for the minuteman companies located further up the road at Concord. As he had several times before, Gage organized a column of troops to capture Adams and Hancock before they departed, and seize the stores from the rebels. Every regiment he commanded wanted to take part in the raid. Because the march to Concord was over 40 miles there and back, he assembled his best troops, the light and grenadier companies, from the regiments in his army.
At 9 pm on 18 April 1775, the tireless Dr. Joseph Warren, one of the few remaining Sons of Liberty in Boston, informed William Dawes and Paul Revere to be prepared to ride. Both Dawes and Revere were couriers for the Sons of Liberty, and Revere had even warned Lexington and Concord of the impending raid two days before. But a general alarm to raise the minuteman companies was beyond Warren’s sole authority. The Massachusetts’s Provisional Council required the five members of the Committee of Public Safety to unanimously vote to raise the alarm. Warren was the only member in Boston. Three were staying at the Black Horse Tavern in Menotomy, across the river, and the fourth was in Charlestown. Traveling and gathering them up for the vote would take time and possibly cause a later alert, if the British moved while he was away. He decided to stay and personally oversee the placing of the lanterns in the Old North Church
Dr. Warren was waiting for the British to move before sending the initial signal. Revere had actually coordinated the system two days before but it was left to Warren to actually initiate it. If Revere and Dawes saw one lantern in the steeple, the British raiding force was moving via the Boston Neck; if there were two lanterns, they moved by boat across the Charles River estuary. They would then alert the countryside of the British Army’s movements and raise the minute companies; Dawes by the Neck and Revere by rowing to Cambridge first. The two riders were to meet Samuel Prescott, a Concord native, just past Lexington to make the journey to Concord. Neither Revere nor Dawes were familiar with the roads west of Lexington and Prescott was to be their guide.
The massing of boats and barges was a clear sign that the British were going to cross the estuary. It was only a question of when it was going to happen. Warren, Revere and Dawes did not have long to wait. It seemed everyone knew what was about except the British troops that were going to participate in the battle. About 9:30pm Lieut. Col. Francis Smith, the commander of the raid was finally informed of the mission.
At 10 pm, 18 April, 1775, 700 troops under Smith and his executive officer, Major John Pitcairn, loaded barges off of the Boston Commons. Dr. Warren immediately had two lanterns placed in Old North Church, and Revere and Dawes departed for Lexington and Concord, rousing minute companies along the way. Their routes were not always safe, Gage sent out officers on horseback to patrol the roads to prevent just such a warning. The British landed at Lechmere Point at 11pm and began their march on Lexington and Concord.