“Dark clouds would mass overhead, and there would be an ominous stillness, as if nature was holding its breath.”
“They expected to mass an army of three hundred thousand men to throw bodily against the invaders and prevent their advance.”
“By doing so, they expected to mass an army of three hundred thousand men to throw bodily against the invaders.”
massify
(transitive and intransitive, anthropology) To become, or cause to become, oriented toward mass production, mass consumption, and high throughput rather than individuality.