General Gage had anticipated that Lt.
Col.
Smith's expedition might require reinforcement, so Gage drafted orders for reinforcing units to assemble in Boston at 4 a.m.  But in his obsession for secrecy, Gage had sent only one copy of the orders to the adjutant of the 1st Brigade, whose servant then left the envelope on a table.
 Also at about 4 a.m., the British column was within three miles of Lexington, and Lt.
Col.
Smith now had clear indication that all element of surprise had been lost and that alarm was spreading throughout the countryside.
 So he sent a rider back to Boston with a request for reinforcements.
 At about 5 a.m., the rider reached Boston, and the 1st Brigade was ordered to assemble: the line infantry companies of the 4th, 23rd, and 47th Regiments, and a battalion of Royal Marines, under the command of Earl Percy.
Unfortunately for the British, once again only one copy of the orders were sent to each commander, and the order for the Royal Marines was delivered to the desk of Major John Pitcairn, who was already on the Lexington Common with Smith's column at that hour.
 After these delays, Percy's brigade, about 1,000 strong, left Boston at about 8:45 a.m., headed toward Lexington.
 Along the way, the story is told, they marched to the tune of "Yankee Doodle" to taunt the inhabitants of the area.
 By the Battle of Bunker Hill less than two months later, the song would become a popular anthem for the colonial forces.

Percy took the land route across Boston Neck and over the Great Bridge, which some quick-thinking colonists had stripped of its planking to delay the British.
 His men then came upon an absent-minded tutor at Harvard College and asked him which road would take them to Lexington.
 The Harvard man, apparently oblivious to the reality of what was happening around him, showed him the proper road without thinking.
 (He was later compelled to leave the country for inadvertently supporting the enemy.)
 Percy's troops arrived in Lexington at about 2:00 p.m.  They could hear gunfire in the distance as they set up their cannon and deployed lines of regulars on high ground with commanding views of the town.
 Colonel Smith's men approached like a fleeing mob with the full complement of colonial militia in close formation pursuing them.
 Percy ordered his artillery to open fire at extreme range, dispersing the colonial militiamen.
 Smith's men collapsed with exhaustion once they reached the safety of Percy's lines.

Against the advice of his Master of Ordnance, Percy had left Boston without spare ammunition for his men or for the two artillery pieces they brought with them, thinking the extra wagons would slow him down.
Each man in Percy's brigade had only 36 rounds, and each artillery piece was supplied with only a few rounds carried in side-boxes.
 After Percy had left the city, Gage directed two ammunition wagons guarded by one officer and thirteen men to follow.
 This convoy was intercepted by a small party of older, veteran militiamen still on the "alarm list", who could not join their militia companies because they were well over 60 years of age.
 These men rose up in ambush and demanded the surrender of the wagons, but the regulars ignored them and drove their horses on.
 The old men opened fire, shot the lead horses, killed two sergeants, and wounded the officer.
 The British survivors ran, and six of them threw their weapons into a pond before they surrendered.
General Gage had anticipated that Lt. Col. Smith's expedition might require reinforcement, so Gage drafted orders for reinforcing units to assemble in Boston at 4 a.m.  But in his obsession for secrecy, Gage had sent only one copy of the orders to the adjutant of the 1st Brigade, whose servant then left the envelope on a table.  Also at about 4 a.m., the British column was within three miles of Lexington, and Lt. Col. Smith now had clear indication that all element of surprise had been lost and that alarm was spreading throughout the countryside.  So he sent a rider back to Boston with a request for reinforcements.  At about 5 a.m., the rider reached Boston, and the 1st Brigade was ordered to assemble: the line infantry companies of the 4th, 23rd, and 47th Regiments, and a battalion of Royal Marines, under the command of Earl Percy. Unfortunately for the British, once again only one copy of the orders were sent to each commander, and the order for the Royal Marines was delivered to the desk of Major John Pitcairn, who was already on the Lexington Common with Smith's column at that hour.  After these delays, Percy's brigade, about 1,000 strong, left Boston at about 8:45 a.m., headed toward Lexington.  Along the way, the story is told, they marched to the tune of "Yankee Doodle" to taunt the inhabitants of the area.  By the Battle of Bunker Hill less than two months later, the song would become a popular anthem for the colonial forces.
Percy took the land route across Boston Neck and over the Great Bridge, which some quick-thinking colonists had stripped of its planking to delay the British.  His men then came upon an absent-minded tutor at Harvard College and asked him which road would take them to Lexington.  The Harvard man, apparently oblivious to the reality of what was happening around him, showed him the proper road without thinking.  (He was later compelled to leave the country for inadvertently supporting the enemy.)  Percy's troops arrived in Lexington at about 2:00 p.m.  They could hear gunfire in the distance as they set up their cannon and deployed lines of regulars on high ground with commanding views of the town.  Colonel Smith's men approached like a fleeing mob with the full complement of colonial militia in close formation pursuing them.  Percy ordered his artillery to open fire at extreme range, dispersing the colonial militiamen.  Smith's men collapsed with exhaustion once they reached the safety of Percy's lines.
Against the advice of his Master of Ordnance, Percy had left Boston without spare ammunition for his men or for the two artillery pieces they brought with them, thinking the extra wagons would slow him down. Each man in Percy's brigade had only 36 rounds, and each artillery piece was supplied with only a few rounds carried in side-boxes.  After Percy had left the city, Gage directed two ammunition wagons guarded by one officer and thirteen men to follow.  This convoy was intercepted by a small party of older, veteran militiamen still on the "alarm list", who could not join their militia companies because they were well over 60 years of age.  These men rose up in ambush and demanded the surrender of the wagons, but the regulars ignored them and drove their horses on.  The old men opened fire, shot the lead horses, killed two sergeants, and wounded the officer.  The British survivors ran, and six of them threw their weapons into a pond before they surrendered.
Battles of Lexington and Concord