2 Kings 9:17

There stood a watchman on the tower— In times of peace as well as war, it was usual to have watchmen set on high and eminent places wherever the king was, to prevent his being surprised. Thus David at Jerusalem was informed by the watchmen, that his sons were escaped from the slaughter of Absalom, when he thought them all lost, 2 Samuel 13:34.; and therefore Jehoram, who had an armor lying before Ramoth-gilead, had good reason to keep a watchful eye upon every motion, especially from that quarter. See Calmet.