<P> 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 . </P> <P> 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 . </P> <P> Percy assumed control of the combined forces of about 1,700 men and let them rest, eat, drink, and have their wounds tended at field headquarters (Munroe Tavern) before resuming the march . They set out from Lexington at about 3: 30 p.m., in a formation that emphasized defense along the sides and rear of the column . Wounded regulars rode on the cannon and were forced to hop off when they were fired at by gatherings of militia . Percy's men were often surrounded, but they had the tactical advantage of interior lines . Percy could shift his units more easily to where they were needed, while the colonial militia were required to move around the outside of his formation . Percy placed Smith's men in the middle of the column, while the 23rd Regiment's line companies made up the column's rear guard . Because of information provided by Smith and Pitcairn about how the Americans were attacking, Percy ordered the rear guard to be rotated every mile or so, to allow some of his troops to rest briefly . Flanking companies were sent to both sides of the road, and a powerful force of Marines acted as the vanguard to clear the road ahead . </P> <P> During the respite at Lexington, Brigadier General William Heath arrived and took command of the militia . Earlier in the day, he had traveled first to Watertown to discuss tactics with Joseph Warren, who had left Boston that morning, and other members of the Massachusetts Committee of Safety . Heath and Warren reacted to Percy's artillery and flankers by ordering the militiamen to avoid close formations that would attract cannon fire . Instead, they surrounded Percy's marching square with a moving ring of skirmishers at a distance to inflict maximum casualties at minimum risk . </P>

Why is the memorial at concord set out the way it is