Deserter's March is an location in Tyranny.
Deserter's March Information
General Walkthrough and Tips
When you first arrive and head north, and be careful to disarm the trap there. Then head left, again being careful to disarm the trap here. There are some Raiders and corpses here. Loot them to acquire a mysterious missive. Head left and all the way up to find Kalea. You can convince her to return home if you pass a Lore (42) check or you can tell her you will convince the Bronze Brotherhood to accept her.
Head right and you'll come upon Locke and Myrek arguing about Raetomonnon. Speak with both of them and then decide who's side you are on. You cannot convince Myrek to defect, so if you side with Locke, you will eventually have to fight and kill him. This will unlock Twin Rivers on the map.
Head right and loot the corpse to find a crude map and then head north to find the (hidden) Agents notes. Then travel to Twin Rivers.