He also served as collector of the port of Wilmington, inspector of posts along the eastern line of the southern coast during the Rutherford B. Hayes Administration, and special agent of the United States Treasury Department.

During the siege of Petersburg, he commanded the 2nd Brigade, 1st Division, X Corps at Chaffin's Farm and the subsequent actions along the Darbytown and New Market Roads.

Although Abbott was not appointed as a full, substantive rank general, on January 25, 1865, President Abraham Lincoln nominated Abbott for appointment to the grade of brevet brigadier general of volunteers, to rank from January 15, 1865 for gallant services in the capture of Fort Fisher[3] and the U.S. Senate confirmed the award on February 14, 1865.

He believed in their capacity and assisted in organization and politically counseling them in ways which brought him blunt warnings from the white population.

During his tenure in the Senate, he spoke in orthodox terms on matters of suffrage, and was helpful in handling the details of army administration.

He devoted a good deal of time to improve the harbor of Wilmington, and hoped that the railroads of the Carolinas would be consolidated and made part of a southern transcontinental system.

He also received federal offices from both Presidents Rutherford Hayes and Ulysses S. Grant, including serving as collector of the port of Wilmington, inspector of posts along the eastern line of the southern coast during the Rutherford B. Hayes Administration, and special agent of the United States Treasury Department.