The Gettysburg battlefield is a giant outdoor classroom clustered with hundreds of monuments. Their stories set in stone, bronze and iron help visitors explore one of the great turning points in American history. The headquarters monuments provide the background to the story. They were erected just before the battle's 50th anniversary in 1913 to give a visitor the big picture and to put into perspective the monuments to the regiments, batteries and individuals. The book showcases all 110 Union brigade, division, corps and army headquarters monuments on the Gettysburg battlefield, each with a photograph, complete text from the monument, map location and GPS information. Also included is an index of the 223 officers (and one sergeant) named on the monuments and a second index of all subordinate regiments and batteries. Each monument names its unit's commanders and subordinate units, gives a timeline of activities in the battle, and lists casualties. Their wording is in the dispassionate and often awkward voice of an official report, but does not conceal the underlying triumphs and tragedies that together make up the story of this largest and deadliest of all Civil War battles. A companion book on Confederate Headquarters Monuments at Gettysburg is also available.