Answer :
General Israel Putnam told his men "Dont fire until you see the whites of there eyes because some of them were too eagar to shoot and he wanted them to shoot at close range so they could hit the enemy. This also saved ammunition and helped them fight better.
Because he was running low on ammunition and didn't want shots being wasted if the soldiers don't hit the enemy. So to ensure they hit the enemy they didn't fire until they were positive they would hit.
