Conscription (drafting them). During the Vietnam War men were taken in belly chains via the US Marshall Service to holding tanks at the Oakland Army Depot in Oakand CA (across the bay from San Franciso). Other men could be seen sitting in chains on the cement steps of various Federal Court buildings awaiting their trials. These groups numbered in their dozens.
All men
According to the CIA World Factbook, there are approximately 12,000,000 men age 16-49 that are fit for military service in the UK.
Required men to register with the govt. for a draft, in order to be randomly selected for military service. May, 1917
Because the men has to do military service
Veterans.
Men and women alike can join the Norwegian Military. However, the Norwegian Military does have a mandatory military service for men which has been described as being weak.
By making military training a part of a college education.
There lines of hungry and unemployed men trying to get into the service. But the service was full up.
Draft men to serve in the military
Probably 300,000
minutemen
Other than military service.