On January 13, 1866, President Andrew Johnson nominated Gregg for appointment to the grade of brevet major general of volunteers to rank from March 13, 1865, and the U.S. Senate confirmed the appointment on March 12, 1866.
On January 13, 1866, President Andrew Johnson nominated Gregg for a brevet major general of volunteers rank effective from March 13, 1865, and the U.S. Senate approved the appointment on March 12, 1866.