[Critter]

From The American Revolution, by Sir George Otto Trevelyan, Longmans, Green and Company, 1903:

...The deadly and personal character of the American sharpshooting was for the British and unexpected and disconcerting phenomenon, and would have altogether daunted less brave troops than those against whom it was directed. "This war," said one English officer, "is very different to the last in Germany. In this the life of the individual is sought with as much avidity as the obtaining a victory over an army of thousands."

Nothing like it had ever been witnessed on the other side of the Atlantic...

The slaughter in the commissioned ranks at Bunker's Hill, as is sure to be the case with an unpleasant novelty, excited moral disapprobation in English circles. "How far," one gentleman wrote, "the Bostonians can justify taking aim at officers with rifled muskets, I am not military jurisprudent enough to determine. It seems to be contrary to justice." There was no question of justice, but of physical and mental custom which had become an engrained instinct. Many a colonist had never fired off a charge of powder without singling out something or somebody, whether it was the chief with the largest bunch of feathers in a rush of indian warriors, or the drake in a string of wild fowl.

[CrazyIvan]

American marksmanship was not just a matter of skill and pride. Shot and powder were scarce. I remember reading about one settler that reused a rifle ball forty some times before loosing it to a miss. I would hate to have been on his bad side!

[HuntsvilleTxVeteran]

"This war," said one English officer, "is very different to the last in Germany. In this the life of the individual is sought with as much avidity as the obtaining a victory over an army of thousands."

This was the first war where the common troops were not used as cannon fodder.

[MissAmericanPie]

"There was no question of justice, but of physical and mental custom which had become an engrained instinct."

Well that has certainly been bred out of a great number of Americans.