Men, you are all marksmen — don't one of you fire until you see the white of their eyes.
Source, in full
At the Battle of Bunker Hill (June 17, 1775), reported in Richard Frothingham Jr., History of the Siege of Boston, &c. (Boston: Charles C. Little and James Brown, 1849), p. 140, footnote: "Philip Johnson states of Putnam: 'I distinctly heard him say, ...'"