"One of the most well known instances of a commander being killed, by a sharpshooter’s minie ball was at Spotsylvania Court House, where US Major General John Sedgwick dressed down his staff members who were ducking when hearing sniper fire, “…they couldn’t hit an elephant at this this distance.” Seconds later, Sedgwick was instantly killed by a sharpshooter bullet to the head. “Uncle John” Sedgwick, in command of the VI Corps, would be the highest ranking Federal officer killed in the war. The shot that killed him was reported to been made from over 1,000 yards."
http://thismightyscourge.com/2009/01/27/sharpshooters-murder-or-accepted-terms-of-engagement/