I am inspired from the TV show The Game of Thrones.
Nights watch is the military order, which is dedicated to holding the Wall, the immense fortification which on the northern border of the Seven Kingdoms; and defending the realms of man from what lies North of the wall. The order foundation dates back to the Age of Heroes, at the time when the Others were pushed back. The men of Night’s Watch wear only black.
They dont have a logo or insignia but they call them self the crows so I put a crow which has little bit of snow on it showing the constant cold of their post.
The light that brings the dawn is a part from Nights Watch oath.