The bluffs on the eastern side rise sharply from the river, forming the high ground where Reno’s men would make their defensive stand and where Custer would move before his fatal encounter with the warriors moving to meet him.

The terrain shaped the battle in ways that neither Custer nor his officers fully anticipated.

The broken ground of the coulees — the dry gullies cut by seasonal runoff from the uplands — concealed the movement of warriors who used them to get into position.

The high bluffs on the eastern side of the river gave some visibility over the valley but also cut off views of what was happening in other parts of the battlefield.

Custer, moving north along the eastern bluffs, was not able to see what was happening to Reno’s men in the valley below.