The Dimmock Line
"The order of work on the general defenses ... should be to occupy the favorable points in the circuit around the place (far enough from the town to prevent the enemy coming within bombarding distance) by suitable detached works, closed toward the town, with stockades. The intermediate spaces to be filled up afterward by rifle-pits or lines of infantry cover. The works to be earthworks, with such obstructions in advance as you may find the means and time to construct, such as abatis, pits, felled timber, & c."
-- Chief Engineer Jeremy F. Gilmer
Charles Henry Dimmock was born in Baltimore, on October 18, 1831. His family afterwards settled in Richmond, where his father became the city surveyor. Dimmock studied mathematics and engineering under Claude Crozet, who was Principal Engineer and Surveyor for the Virginia Board of Public Works and a founder of the Virginia Military Institute. Under Crozet's direction, Dimmock worked as engineer on various civil projects in Virginia -- primarily roads and railroads. With the start of the Civil War, Dimmock was commissioned captain of engineers in the Confederate States Army. Undoubtedly, his career was aided by the fact that his father, Col. Charles Dimmock Sr., was by this time Chief of Ordnance for the state of Virginia and Inspector of Richmond's fortifications.
Despite a lack of military experience, one of Dimmock's early war assignments was to oversee construction of fortifications on Roanoke Island, North Carolina. These works were not considered successful. He then returned to Virginia to oversee work on the Yorktown fortifications with others. As McClellan's army moved up the Peninsula toward Richmond, Capt. Dimmock was sent to Petersburg to obstruct the Appomattox River to stymie the approach of Union gunboats. Dimmock then worked on a new military railroad bridge over the Appomattox.
With the departure of Gilmer and Stevens, Capt. Dimmock inherited the formidable task of fortifying the city. Military affairs in North Carolina in November and December drew off most of the soldiers and slave owners demanded the return of their property, leaving him starved for labor. Dimmock solved the problem by establishing a skilled cadre of 200 free black and slave workers who worked from 8 am until 4 pm daily for regular wages. After that, the work proceeded slowly but steadily.
Anticipating attack from the direction of City Point, much labor was lavished on the eastern front from the Appomattox River past the Jerusalem Plank Road. Beyond that the works were more or less sketched in -- artillery batteries were started, connecting infantry lines were left until manpower was available.
Despite a lack of military experience, one of Dimmock's early war assignments was to oversee construction of fortifications on Roanoke Island, North Carolina. These works were not considered successful. He then returned to Virginia to oversee work on the Yorktown fortifications with others. As McClellan's army moved up the Peninsula toward Richmond, Capt. Dimmock was sent to Petersburg to obstruct the Appomattox River to stymie the approach of Union gunboats. Dimmock then worked on a new military railroad bridge over the Appomattox.
With the departure of Gilmer and Stevens, Capt. Dimmock inherited the formidable task of fortifying the city. Military affairs in North Carolina in November and December drew off most of the soldiers and slave owners demanded the return of their property, leaving him starved for labor. Dimmock solved the problem by establishing a skilled cadre of 200 free black and slave workers who worked from 8 am until 4 pm daily for regular wages. After that, the work proceeded slowly but steadily.
Anticipating attack from the direction of City Point, much labor was lavished on the eastern front from the Appomattox River past the Jerusalem Plank Road. Beyond that the works were more or less sketched in -- artillery batteries were started, connecting infantry lines were left until manpower was available.
Federal Maps of a portion of the Dimoock Line produced during the assaults on Petersburg
Federal engineers made detailed plans and drawings of that portion of the Dimmock Line that was captured during the fighting of June 15-18, 1864. This included the works from Battery 1 on the Appomattox River to Battery 24 near the Norfolk & Petersburg Railroad.
These maps and the original survey drawings that follow are in the National Archives. The images reproduced here are from the collection of Petersburg National Battlefield.
These maps and the original survey drawings that follow are in the National Archives. The images reproduced here are from the collection of Petersburg National Battlefield.
Pages from the surveyors' book, showing individual segments of the Dimmock Line
The following images (likely all by Timothy H. O'Sullivan) show the massive scale of the works built on the Dimmock Line. The redoubts were designed to give the artillery a commanding height over the ground to its front, in the style of a rampart topped by a parapet.

LC 01229. "[Petersburg, Va. Redoubt near Dunn's house in outer line of Confederate fortifications captured June 14 [sic], 1864, by Gen. William F. Smith]," stereograph by Timothy H. O'Sullivan. Looking into the front ditch of Battery 11. Federals dug a firing step into the outer face of the parapet to fire in the opposite direction.
Several of the Dimmock works were reversed by the Federals to fire west instead of east. Some elements of the original Confederate lines can be picked out of the following images, including a magazine, and large, nicely constructed wooden platforms for the guns.
updated 03/12/2019