
It's from Maester Aemon of the Night's Watch.
Their Lord Commander is dead.
Game of Thrones Season 3, Episode 10

CERSEl: Lord Janos Slynt
was COMMANDER of the City Watch.
Game of Thrones Season 2, Episode 2

I traveled south under orders
from the Lord Commander.
Game of Thrones Season 6, Episode 6

Commander:
Shoulder arms!
Westworld Season 2, Episode 3

( samurai COMMANDER
drilling troops )
Westworld Season 2, Episode 5