Reciprocity and repeatability. If you don't look after those who looked after you then you will find it very hard to get help in the future.
Ah so people should work for the occupiers so they can emigrate


And a serviceman may be used for a Gambit, but too many of those and you will find it hard to recruit any.
Conscription

That is why there are big parades, statues and shiny bits of metal pinned to their chests... its all there to get more recruits.
Yeah well some people will be gullible enough to buy that window dressing , but for me a statue of some dead bloke or a cripple with a shiney bit of metal on a ribbon doesn't really give much encouragement does it .
The US is finding that bigger and bigger chunks of cash for those that sign up work quite well though .