The lack of a draft has begun to create a military caste within America that has caused very few families to carry the burden of many. The freedoms and privileges we all enjoy should be maintained by all Americans not just a select few. The option of civil service will also create a way for people who would not be interested in military duty for religious or any other reason to opt out of combat while still contributing.
19 would be a target age and exemptions to postpone the service until after college would be available.