1. Voluntary Enlistment:
- In many countries, men were encouraged to volunteer for military service. Patriotic fervor, a sense of duty, and the promise of adventure motivated individuals to sign up for the armed forces.
2. Conscription:
- Conscription, also known as mandatory military service, was implemented in several countries to ensure sufficient manpower for the war effort. Men of certain age ranges were required to register and serve unless they met specific criteria for exemption.
3. Selective Service System (United States):
- In the United States, the Selective Service Act of 1917 introduced the draft system. Men between the ages of 21 and 30 were required to register, and a lottery was conducted to determine who would be called to active service.
4. Recruitment Campaigns:
- Governments launched extensive recruitment campaigns using posters, speeches, and other forms of media to encourage men to join the military. These campaigns highlighted the importance of defending one's country and portrayed military service as an honorable and patriotic duty.
5. Professional Soldiers:
- Some men were professional soldiers who had chosen military service as a career. They were already serving in the military before the war and continued their service during World War I.
It's important to note that the signing-up process and criteria for enlistment varied from country to country. Some nations relied solely on voluntary enlistment, while others implemented a combination of voluntary service and conscription to meet their manpower requirements.