I’m of two minds about national service. On one hand, it seems like a powerful tool to build national unity. On the other hand, I see a lot of risk that people will be forced to serve in ways that offend their conscience.
My main reference point is the US during the Vietnam War. Lots of people were conscripted and sent to fight in a war they didn’t believe in. Being a conscientious objector was a thing, but the criteria were very narrow, such that (for example) I would not have qualified even though I consider it an immoral war. The main way people got out of serving was though the exemption for people getting university degrees, but that of course is a very unfair system that only benefits people who are privileged enough to attend a university.