This quest begins after a conversation with the Duke of Hernand - which takes place at the end of the "News" quest. The Duke offered to help you get to Calphade in order to find the next member of the Greymanes.
A guide is waiting at the beacon. Make haste.
Go to Torchlight Beacon - a tower standing on a hill west of Hernand - and speak with the soldiers you meet there. One of them is your guide.
Mount your horse and follow your guide.After some time, you will reach the ambush site. Your guide will dismount and begin investigating the area, the soldiers' bodies, etc.
Actually, you don't have to do anything, just wait while your guide explores the area a bit. A cutscene will trigger, and shortly after, you will be attacked by several Black Bears. You must kill them all before you can move on.
Fighting them is an opportunity to learn a new skill - Clothesline.
Once all the enemies are dead, mount your horse again and continue following your guide. After a while, without further incident, you will reach the Calphade Gate where your guide will leave you.
Approach Marshal Middler to begin the conversation. Follow him and listen to what he has to say. Once you have heard everything he has to tell you - the quest will end and the next one will begin.
Signs of the Black Bears' assault on the road to Calphade revealed how dire the situation is. Upon arrival, Marshal Middler stressed just how bad things had become, but you pushed forward toward the front lines to save your comrade.
