Maedhril has a plan to deal with the Orc-archers, and it involves both your help and a very large fire.
'The Orc-scouts that prowl throughout Caranost carry bows with which they have proven quite deadly. Defeat these scouts and gather up their bows. Then climb to the tower from which you could spy on Sírlond, and burn the bows in the fire the Orcs built.
'I will watch for the smoke of the burning, and so I will know when the Orcs have received the message. What message? Simply this, my helpful messenger: that their archers will not be allowed to strike us from afar.'
Maedhril asked you to defeat Caranost scouts and retrieve their bows.
The tower overlooking the bridge at Caranost holds a large bonfire at which Maedhril wanted you to burn the Orc-bows.