How did military outposts communicate along the great wall of china?

Question

how did military outposts communicate along the great wall of china

Answer 1

According to the history channel/PBS smoke signals and fire, depending on the time of day .  . . day or night. One fire or puff of smoke signaled that there were under 100 attackers, two fires or puffs of smoke indicated less than 500 attackers, 3 fires or puffs of smoke signaled less than 1000 attackers, and 4 fires or puffs of smoke signaled 5000. The signals were passed down the line so that the head honchos knew how many soldiers to send when a section of the wall was breeched.

As a prank, they would send false signals to get the troops to rush to their aid, and after awhile it backfired and nobody came to help. Supposedly this is where the phrase, "the little boy who cried wolf" stems from . . . .   just found another source

Answer 2

I'm not sure, but i'm guessing flags during the day and large torches during the night.