Patriots Day commemorates the start of the American Revolution, the battles of Lexington and Concord on April 19, 1775, and the staggering British retreat to Boston. What's less known is how the Americans outfoxed the British at one of their own strengths, intelligence.
Those opening clashes of the revolution revolved around a spy-vs-spy game -- when and how were the British going to surprise rebel leaders in Lexington and then destroy the stores of munitions at Concord.
And, after the day of fighting was over, there was a second competition for spreading news of the events, what today we might call "information war." The Americans won that contest, too.
Yet, 236 years later, these intelligence coups are little remembered. Casual historians may recall "The Midnight Ride of Paul Revere" -- a dramatic part of thwarting the British surprise -- but few recall the exploits of Dr. Joseph Warren, arguably America's first spymaster.
Though involved with the Sons of Liberty and a member of the Boston Committee of Correspondence, a key body in organizing the revolution, Warren moved within Boston's respected society as a physician and surgeon. Indeed, that may have put him in place to recruit one of the most important and still mysterious spies in American history.
In the turbulent years leading up to hostilities, Warren collaborated with fellow patriot Paul Revere in constructing a remarkable intelligence network for its time, a loosely knit collection of sympathetic citizens who uncovered information about the British garrisoned in Boston. The network also included riders who could spread alarms quickly through the countryside.
Warren and Revere oversaw an effective system of propaganda, too, highlighting excesses committed by the British and pioneering the use of fast clipper ships to distribute their side of the story across the Atlantic.
Their intelligence network was tested in spring 1775 as the British prepared for what King George III hoped would be a decisive strike against the rebellious New Englanders, including the arrest of top leaders, John Hancock and Samuel Adams, hiding out in Lexington. Their whereabouts had been detected by British General Thomas Gage's own spies.
But the Warren-Revere network usually was a step ahead of Gage's team. Keeping a close tab on British movements, the patriot spies learned two key facts, that British agents had scouted routes toward Concord and that British longboats were lowered into Boston Harbor on April 6.
On April 8, expecting an imminent attack, Warren prepared an urgent warning to the patriots in Concord, telling them that "we daily expect a Tumult," and that Concord would be the target with an assault possibly the next day. Revere carried Warren's message by horseback.
Although Warren's date proved incorrect, he was right about one of the Redcoats' key targets, Concord. The patriots were on high alert.
On his way back to Boston, Revere had the prescient thought that the British might try to seal off Boston before their attack and thus he devised a signal with patriots across the Charles River in Charlestown that could be used as a back-up plan. Lanterns would be hung from Boston's Old North Church, one if the attack came by land, two if by sea.
Gage soon learned from loyalist spies that Revere had carried Warren's message to Concord. So, in readying the April 19 march on Lexington and Concord, Gage dispatched mounted patrols of 20 officers and sergeants into the countryside on April 18 to cut off warnings from American riders trying to spread the alarm to local militias.
The final chapter of this intelligence cat-and-mouse game would determine whether the British would retain an element of surprise, or whether Warren and Revere could ensure that the Redcoats would be met by an armed citizenry.
By the afternoon of April 18, a bustle of British activity in Boston had been detected by local residents sympathetic to the patriots. Reports were flowing into Warren's medical office, his make-shift intelligence headquarters.