'Mustering' in the Bible

So the Spirit of the LORD took control of Gideon, who blew a trumpet, mustering the descendants of Abiezer to follow him into battle.

"Listen! There's a noise on the mountains like that of a great multitude! Listen! There's an uproar among the kingdoms, like that of nations massing together! The LORD of the Heavenly Armies is mustering an army for battle.