These are the ways in which the soldiers were summoned. A banner was raised on top of a bare mountain to ensure visibility from afar. It was customary in ancient times to summon troops by putting such signals in conspicuous places.
The soldiers are also called by shouting and waving. Thus three different ways are used to call them together, which shows the urgency of the summons.
2 On a bare hill raise a signal; cry aloud to them; wave the hand for them to enter the gates of the nobles.