[h4nkoslo]

The traditional answer is various ways of forced community-building (collective punishment & reward, forming in/outgroups, etc) as a way of building loyalty to their individual unit.

Also note that in modern militaries, the ratio of behind-the-lines support troops to front-line trigger pullers is absurdly high. Depending on the country, you can end up with conscripts e.g. running the vehicle pool and doing logistics while the core infantry is essential volunteer.