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 was 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 rearguard. 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. 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. A few mounted militiamen on the road would dismount, fire muskets at the approaching regulars, then remount and gallop ahead to repeat the tactic. The unmounted militia would often fire from long range, in the hope of hitting somebody in the main column of soldiers on the road and surviving, since both British and colonials used muskets with an effective combat range of about . Infantry units would apply pressure to the sides of the British column. When it moved out of range, those units would move around and forward to re-engage the column further down the road. Heath sent messengers out to intercept arriving militia units, directing them to appropriate places along the road to engage the regulars. Some towns sent supply wagons to assist in feeding and rearming the militia. Heath and Warren did lead skirmishers in small actions into battle themselves, but it was the presence of effective leadership that probably had the greatest impact on the success of these tactics. The fighting grew more