Why did people have to join the army trench warfare?

Answer 1

The draft is the reason why people "have" to join the army. During WW1, in which previous to both WW1 and WW2, we seem to be isolationist; the U.S. had mandated the draft due to lack of Volunteers and the need to have a militaristic economy for a period of time to boost the economy which was not doing very well.

Answer 2

People had to join the army in trench warfare due to various reasons. Some joined out of a sense of duty and patriotism to defend their country. Others were compelled to join through conscription or because of economic reasons, as military service offered a steady income and job security. Additionally, social pressure and the desire to support their comrades and protect their loved ones could have motivated individuals to join the army.