My ex was career military. It was his dream career, the only thing he wanted since childhood. But, like anything, for some people it isn't so voluntary. The American military is more "color blind" and thus a better opportunity for black Americans than many civilian jobs. So when the Gulf War broke out, blacks were "overrepresented" in the military and this became a political hot potato: What had been a good opportunity in peace time was now a serious risk to life and limb for an inordinately high number of blacks and this was seen as another form of racism in America, basically.

Plus, in many countries there is a compulsory term of service.