Who was the highest ranking Civil War General?

MAJOR GENERAL JOHN SEDGWICK KILLED ON MAY 9 1864 AT THE BEGINNING OF THE BATTLE OF SPOTSYLVANIA COURTHOUSE.

Phillip Kearny was senior to Sedgwick by date of rank as a major general. Also James B. McPherson was a department and army commander at the time of his death, which in essence made him higher ranking than any major general who did not hold such a presidential appointment.