While British and American regulars battled on the 3rd line at Guilford Courthouse (parts 9-13 in this series), a separate battle took place in the woods to the south. There, Regiment von Bose and the 1st Battalion of Guards advanced against the American light troops in Lieutenant-Colonel Henry Lee’s flank corps.
The British troops were at a disadvantage in the heavily wooded terrain. Commissary General Charles Stedman later wrote:
[The Guards] suffered greatly in ascending a woody height to attack the second line of the Americans, strongly posted upon the top of it, who, availing themselves of the advantages of their situation, retired, as soon as they had discharged their pieces, behind the brow of the hill, which protected them from the shot of the guards, and returned, as soon as they had loaded, and were again in readiness to fire. 
The Guards at last seized this hill and pressed on to attack another line of Americans. However:
the battalion was not in regular order when it received the fire of the third American line. The enemy’s fire… poured in not only on the front but flank of the battalion… [until] it was at last entirely broken. Fortunately, at this time, the Hessian regiment of Bose… was advancing in firm and compact order on the left of the guards, to attack the enemy.
The Hessians then wheeled to their right, engaged the Americans, and allowed the Guards to rally. Stedman added:
No sooner had the guards and Hessians defeated the enemy in front, than they found it necessary to return and attack another body of them [the Americans] that appeared in the rear; and in this manner were they obliged to traverse the same ground in various directions, before the enemy were completely put to the rout.
The troops to the rear were probably the Rockbridge Rifles of Brigadier-General Edward Stevens’ brigade of Virginia militia. These troops held a part of the woods in between the British troops in the separate battle and the rest of the British army; thus, they remained on the American second line long after the rest of the Virginia militia had retreated.
The Virginians at last got into action with the 1st Guards. According to Samuel Houston:
we fired on their flank, and that brought down many of them… We pursued them about forty poles [220 yards] to the top of a hill, where they stood, and we retreated from them back to where we formed. Here we repulsed them again; and they a second time made us retreat back to our first ground, where we were deceived by a reinforcement of Hessians, whom we took for our own [both Hessians and Continentals wore blue coats], and cried to them to see if they were our friends, and shouted Liberty! Liberty! and advanced up till they let off some guns; then we fired sharply on them, and made them retreat a little. 
Regiment von Bose drives Virginia riflemen and North Carolina militiamen through the woods at the beginning of the separate battle (here and below, click to enlarge).
In the foreground, the 1st Battalion of Guards struggles against the Rockbridge Rifles. In the background, Regiment von Bose attacks the flank of Lee’s flank corps.
Another view of the above.
1. Charles Stedman. (1794). The History of the Origin, Progress, and Termination of the American War, Vol. 2.
2. Houston's account appears in William Henry Foote (1855). Sketches of Virginia....