We find several references in scripture to a watcher mounting the city walls in times of stress to survey the scene outside the fortifications. He was situated on a spot from which he could monitor the approaches to the town. If a threat appeared, he would sound a warning and the town would shut its gate. Watchman's Signal -- Sounding the in perilous times
Ezekiel 33:6 KJV But if the watchman see the sword come, and blow not the trumpet, and the people be not warned; if the sword come, and take any person from among them, he is taken away in his iniquity; but his blood will I require at the watchman's hand.
2 Timothy 3:1 KJV “This know also, that in the last days perilous times shall come.”