Elden Ring PC | Site of Grace run - from Stormhill Shack to Castleward Tunnel

Just like in other Soulsborne games, if you're having problems with the NPCs of an area, you can sometimes run past them. In this case, I did not.

Before clearing the rest of the area, I go back for that pat at 0:19 so if and when when one of the soldiers blows the horn, I don't have to deal with them coming at me from behind.

Castleward Tunnel
This tunnel leads into Stormveil Castle, but is blocked by Margit the Fell Omen, the first mandatory boss of the game. This site of grace is just before that boss fight.
You can read more about Castleward Tunnel here:
https://eldenring.fandom.com/wiki/Castleward_Tunnel