So, I'll go with a famous event today. In hopes of arresting some Rebels and destroying caches of weapons, Major John Pitcairn approached Lexington Green with six companies of British Regulars. They had captured Paul Revere earlier and knew they were expected. Revere misled them into believing there were 500 men awaiting them at Lexington, so Colonel Smith sent a message to General Gage in Boston for reinforcements. Pitcairn and his troops met up with only seventy militiamen on the village green, under command of Captain John Parker. Both commanders ordered their troops not to fire. Pitcairn ordered the militiamen to disperse: under orders from Parker, out of concern for his troops, some did. Others held their ground.
Who fired first will never be known, but someone fired and the battle begun. Pitcairn maintained to his death that a musket fired from behind a stone wall, starting the whole thing; while Parker reported that the Regulars charged the militiamen and started it. Does it really matter who started it? No. It was probably a little of both. Regardless, the Regulars, frustrated, ignored Pitcairn's orders to stop firing until he ordered a drum roll. When it was over, eight militiamen were dead (reportedly shot in the back) and seven wounded. Colonel Smith arrived with his troops shortly thereafter.
The Regulars left Lexington and made their way to Concord, where they encountered no resistance at first. They searched the houses for stores and, for the most part, were quite decent about it. Robert A. Gross feels it was because they were trying to avoid a repeat of the fight at Lexington. The militiamen, under Colonel James Barrett, had positioned themselves above the North Bridge, which they felt they needed to hold. As the day and the search wore on, they were reinforced by others from the area. When they saw smoke rising from Concord (from a fire set by Regulars that was quickly put out due to the pleading of a widow named Martha Moulton) the militia advanced on the Regulars stationed on the other side of the bridge. The Regulars fired a warning shot, but the militia kept marching. Then the Regulars fired into the militia: the militia kept coming. The Regulars broke and ran and in two or three minutes the militia had beaten them.
Pitcairn then ordered his troops to return to Boston. They hadn't arrested any of their list, but they had destroyed quite a bit of American supplies that had been hidden. As they marched the way they came, they encountered snipers and small contingents of militiamen the entire way. When they got to Lexington, the Regulars met up with the reinforcements Smith had sent for, commanded by Lord Percy. He returned sniper fire and set fire to houses as they made their way to Charlestown, then a few days later Boston (after abandoning Bunker Hill). The final numbers were 73 Regulars dead, 174 wounded, 26 missing; 49 colonists dead, 39 wounded, 4 missing.
The Minutemen and Their World: Robert A. Gross
The American Spirit, Vol. 1: Thomas A. Bailey
The Outline of History: H.G. Wells
Wikipedia: The Battles of Lexington and Concord