At Guilford Courthouse, the British army was met by artillery fire as it neared the Americans’ defensive lines. The British commander, Lieutenant-General Charles Cornwallis, responded by sending his own guns into action and by deploying his infantry for battle.
A gunner of the Royal Artillery fires a 3-pounder.
Soon, the British line swept forward. On the right of the line, Major-General Alexander Leslie led the 2nd battalion of the 71st Foot (Fraser’s highlanders) and the Hessian Regiment von Bose. The former ascended a long muddy field. The latter struggled across a creek and ravine parallel to its path. On the far side of the creek, the left wing advanced up a wooded ravine, while the right wing burst into a small field, whose far end was defended by riflemen and light infantry. The British soon ordered up the 1st battalion of Guards to prevent the Hessians from becoming outflanked.
The 71st Foot (in red) and Regiment von Bose (in blue) advance against a portion of the American first line.
In the ‘separate field,’ Regiment von Bose faces American riflemen and Lee’s Legion.
On the left of the line, Lieutenant-Colonel James Webster led two much esteemed regiments: the 23rd Foot, the famous Royal Welch Fusiliers, and the 33rd Foot, a regiment nicknamed ‘the Pattern,’ for it was regarded as a model for the rest of the army. 
The Fusiliers kept pace with the Highlanders on open ground. Referring to these two regiments, Sergeant Roger Lamb of the Fusiliers later recalled:
“After the brigade formed across the open ground, the colonel [Webster] rode on to the front, and gave the word, “Charge.” Instantly the movement was made, in excellent order, in a smart run, with arms charged…”
Meanwhile, the 33rd struggled to cross difficult, wooded terrain. There, they were soon joined by a company of Jaegers and Guards light infantry. Cornwallis, it seems, wanted to ensure that he was not outflanked.
The 23rd Foot advances alongside the Highlanders, while the 33rd Foot crosses through the woods. The British brigade of Guards can be seen in reserve at far right.
Meanwhile, the Americans made adjustments of their own. Captain Singleton’s battery, which had greeted the British advance, limbered up and prepared to withdraw to the third line after the British infantry got in motion.
On the far right of the American line, some of the men in Lieutenant-Colonel William Washington’s flank corps attempted to assail the vulnerable British left. Colonel Charles Lynch was ordered to send “a Detachment of fifty of his best Riflemen to flank the Enemy” 
Into firing range. In the center fields, the 23rd and 71st regiments are 100 (scale) yards from the North Carolina militia. The first volleys are about to be fired.
1. Lamb's account of the battle (among others) can be found in this compendium.