From 'Buffalo Days,' Forty Years In The Old West, by Homer W. Wheeler published in 1925 by A.L. Burt Company, New York, Chicago. The quote is from pages 184-185:
'We went over the Custer battlefield pretty thoroughly and located the spot where Captain Keogh and several of his men of Company I had followed him. Here was a slight depression in the ground. Evidently at one time it had been a buffalo wallow, and the wind had blown out the dirt, form ing a semi-circular depression covering several yards. The graves were around this depression. The men were buried where they fell, which clearly showed that their position had been taken for defense. This was the only position we found where it looked as if a defense had been made, for the men had fallen all over the battlefield, here and there.'