Much of the history of the War of Independence is explainable in terms of the British inability to grasp the seriousness and the sheer extent of the resistance they were to encounter from the rebels.

Professional European military forces were trained in a type of conventional combat in which armies marched and confronted each other in set-piece battles. One would think that in the North American theater of the Seven Years' War, the British would have realized that a different manner of fighting was possible in which combatants shot at the enemy from concealed positions, as occurred when Braddock's army was ambushed early in the conflict. Apparently, the lessons of that earlier war were forgotten by 1775. When the British expedition to seize the stores of powder and other supplies on April 18–19 began, a coherent resistance by the Americans was not expected. The confrontation at Lexington, though unsuccessful in stopping the movement of British troops, was a surprise encounter to an army that had not anticipated a breakout into open warfare and even the relatively small number of casualties on Lexington Green.

At Concord Bridge, the resistance was stronger and, as schoolchildren used to know from Emerson's famous poem, the "embattled farmers" succeeded in repelling the British attack. This in itself wouldn't necessarily have been decisive were it not for the fact that rebels began firing from concealed positions all along the route back to Boston, making the British retreat a nightmare. None of this would have been possible if the Americans hadn't already had an information network in place throughout the countryside outside Boston. If Revere had not carried out his soon-to-be legendary ride, someone else would have, because the Patriots were well organized in a manner that the British officers in Gage's command could not have imagined.

The additional factor is that, although the goal of the British movement was to seize powder and supplies, the rebels along the route between Boston and Concord were already well armed. In Britain and Europe as a whole, the ordinary people did not generally own firearms as they did in the Colonies. It was a fundamental mistake for the British to assume the general Massachusetts population was unarmed and cowed by the presence of a professional army. All these factors not only led to the failure of the British expedition at Concord, but were repeated throughout the war, in which the Patriot resistance was consistently underestimated or simply not taken seriously by His Majesty's commanders.