When in an area that's been "fortified" with Fortify Area, you resist being surprised, becoming frightened, and all mediator tradecrafts. You also gain these benefits when you use Brace as long as you remain stationary and while performing "guard duty". Whether or not something counts as "guard duty" is up to the discretion of the GM. Being on the front lines in a normal combat encounter would not typically count, but some cases that might are as follows.
When in an area that's been "fortified" with Fortify Area, you resist being surprised, becoming frightened, and all mediator tradecrafts. You also gain these benefits when you use Brace as long as you remain stationary and while performing "guard duty". Whether or not something counts as "guard duty" is up to the discretion of the GM. Being on the front lines in a normal combat encounter would not typically count, but some cases that might are as follows.