What did nations do to increase the size of their armies?
They forced prisoners into their armies.
They created conscription programs.
They allowed women into their armies.
They allowed twelve-year-olds to join.

They created conscription programs.

Explanation:

"Conscription is the compulsory participation in the national military service. Although, there has been evidence of conscription at different periods, the modern system dates back to the French Revolution. It usually involves only men, although some countries have established conscription for both genders. Conscription contributed to the development of large, powerful armies."

lewis and clark (i think)