Below Marye's Heights a Georgia brigade under Brigadier General Thomas R. R. Cobb poised along a 600-yard portion of the Telegraph Road, the main thoroughfare to Richmond. Years of wagon traffic had worn down the surface of the roadway lending it a sunken appearance. Stone retaining walls paralleling the shoulders transformed this peaceful stretch of country highway into a ready-made trench. Jackson's end of the line possessed less inherent strength. His command post at Prospect Hill rose only 65 feet above the surrounding plain. Jackson compensated for the weak terrain by stacking his four divisions one behind the other to a depth of nearly a mile. Any Union offensive against Lee's seven-mile line would, by necessity, traverse a virtually naked expanse in the teeth of a deadly artillery crossfire before reaching the Confederate infantry. Burnside issued his attack orders early on the morning of December 13. They called for an assault against Jackson's corps by Major General William B. Franklin's Left Grand Division to be followed by an advance against Marye's Heights by Major General Edwin V. Sumner's Right Grand Division. Burnside used tentative, ambiguous language in his directives, reflecting either a lack of confidence in his plan or a misunderstanding of his opponent's posture -- perhaps both.