An article long ago discovered which I have hunted up. As mentioned Mr. Lemmon interviewed participants over time, most notably 'Walking Blanket Woman' who rode into the Custer fight beside Rain in the Face, painted with crimson and upon her black horse. She saw soldiers on horseback on a bluff just across the river as she returned to her lodge before Reno's command opened fire. This would be around the time Lt. Varnum dismounted and observed the gray horse troops across the river.
Lemon concluded from his research that after coming under heavy attack, Custer succeeded in extricating more than half of his men but would not abandon Keogh, Calhoun and Smith cut off and surrounded. Chargeing northwest along the right hand side of the slope expecting to cut through but they were killed and Custer doomed.