Studies of the picture and commentary indicates that Jennison is actually portrayed not Lane.
Most folks think the Major General comment is a direct barb at Major Gen'l Thomas Ewing. Ewing was the source of Gen. Order #11 (1863) that so upset Bingham. He was at the time only a Brigadier General in 1863. One must remember the painting was done post war, 1868 I think. Ewing was promoted to Major Gen'l in 1865 and would have had that rank at the time of the painting release and tour.
John R.