I remember in elementary school being told that a drummer would be used to give orders to soldiers from the general in charge of a battle, which seems a bit hard to believe because it would be nearly impossible to hear a drum from far away. If that’s not how a commander delivered orders, how would they do it!
Fife and drum certainly communicated orders on the battlefield, but it was not the only way. The pitch of fifes and the rumble of a snare drum could cut through some of the din of the battlefield. The British army of the 1700s regulated that every company of a regiment would have one drummer, while the grenadier company would have two fifers. However, some regiments maintained to have additional drummers or fifers against the regulation such as the 54th with three fifers in 1773. Bugles would also be used by horse regiments and some light infantry, with a whistle being used as well. Bugles and whistles could be held with one hand, a necessity with someone on the back of a horse. Townsend's rules of the light company encouraged it saying:
these signals must be made by a loud whistle, a posting horn, or some other instrument capable of conveying a sufficient sound to be heard at a considerable Distance, and the stoutest of the Drummers is to be taught to sound these instruments by directions from the Commanding Officer .
Musket fire was loud and the addition of cannons, screaming, enemy fire, etc. meant that an instrument had to pierce through. Fifes and drums would be the best with horns and whistles next up in use. Highland regiments did have bagpipers in their rolls as well. Instead of having fifers in the grenadier companies, they would have two pipers. The Highland regiments that served in the American War of Independence had pipers on their muster rolls, but so far, no sources have said if they came with them on the battlefield.
These musicians would be taught the certain beatings or notes to convey certain orders, and the soldiers would train along with them to be familiar. The British drummers had 15 beats to use for both the battlefield and camp such The Reveille, The Church Call, The Retreat, The March, etc. The cadence of the drum would also help make sure the soldiers stayed at the same pace when marching, presenting arms, firing, and fixing bayonets. All to ensure uniformity the best as possible when in the line. The regiment commander would also have a pair of drummers with him to communicate his orders to other company commanders. Officers of the regiments and field officers would have formed a prior battle plan and they tried to stick by it as best as possible. Each regiment worked like cogs in a clock with the field commanders overseeing the battle and corresponding orders to each regiment. This did not mean that regiments or even companies had no independence on the field. During the later American War of Independence, British regiments would often have orders go down to the company level. For those not aware, a regiment had ten companies made up of: a Light infantry, a grenadier, and 8 "hat" or battalion companies. A captain ran each company with two subalterns. While orders from the top were spread throughout, the regiments did depend on independent thought of officers to counter any attack.
Drummers also assisted in the wounded on the battlefield, carrying them off the field if need be as noted by Private William Burke of the 45th Regiment of Foot, writing of the Hon. Lt. Col. Henry Monckton.
"In this engagement my colonel was wounded. He had two balls shot through his body, and was taken from the field, supported by two drummers."
Each regiment would have their own surgeon and surgeon assistant, so wounded would be taken to them for medical care.
Drummers and fifers would be dressed in reverse colors unless they are in a royal faced regiment. For example, the 10th Regiment of Foot had a redcoat with yellow facings so their musician coats would be yellow with red facings and trimmed with lacing in the musician pattern. However, the 42nd Royal Highlanders had a redcoat and blue facing - denoting royal status, which mean the coats would stay relatively the same but with lacing on the arms and wings on the shoulder. This was to present to the commanders their position but also show the enemy that they were unarmed soldiers.
Steven Baule, "Drummers of the British Army during the American Revolution."
Raoul Camus, Military Music of the American Revolution.
Bennett Cuthbertson, " The Cuthbertson's System, for the complete interior management and œconomy of a battalion of infantry" 1776.
Matthew Spring, With Zeal and Bayonets Only. 2009
John Williamson, The Elements of Military Arrangement; Comprehending the Tacktick, Exercise, Manoevers, and Discipline of the British Infantry, with an Appendix, containing the substance of the principal standing Orders and Regulations for the Army, London: John Wiliamson, 1781, Page 7