Martin Reuben Merritt Wallace (September 29, 1829 – March 6, 1902) was a Union Army officer from October 12, 1861, to November 3, 1864, during the American Civil War.

In recognition of his service, in May 1866, he was nominated for appointment and confirmed to the grade of brevet brigadier general of volunteers, to rank from March 13, 1865.

In 1839, the family moved to Ogle County, Illinois, near Mount Morris, where Wallace's father was a trustee of the Rock River Seminary.

Martin R. M. Wallace assumed control of the 4th Illinois Cavalry Regiment following the death of Colonel William McCullough in December 1862.

[1] On May 4, 1866, President Andrew Johnson nominated Wallace for appointment to the grade of brevet brigadier general of volunteers (an honorary commission in recognition of his service in view of the fact he was no longer an army officer), to rank from March 13, 1865, and the United States Senate confirmed the appointment on May 16, 1866.