These northernmost fortifications along Brook Road served as an early warning system for Confederate troops defending Richmond. Artillery earthworks on each side of the road blocked sudden enemy advances against the capital, and a shallow trench line protecting infantrymen with rifles connected them. If necessary, soldiers and cannons at this forward position could be withdrawn to the Intermediate Line. The parapets of this battery position originally stood 8-10 feet high and at least 15 feet thick at the top, with the inner face supported by posts and heavy logs. Constructed in 1862 largely by a black labor force, the earthworks were occupied intermittently by Confederate troops until the end of the conflict in 1865.