The purpose of armies in most countries (dare say 'all' countries) is to defend the wealth and privilege of the small number of people who control it. Look at the underlying causes of all the huge wars of the last hundred years. The popular mantra of fighting WW1 and 2 is that our ancestors were fighting for freedom against evil aggressors.

Well if you were in Poland I guess that's true - their army was indeed fighting an intruder. For the rest, it was a matter of fighting a potential threat over who controls future wealth (trade, shipping lanes, access to energy sources, foreign influence, etc).

The UK was being warned to ensure it 'uses' its wealthy 'security guards' in Afghanistan or it might have found itself short of men to ward off future threats to so-called "British interests" - which by and large aren't the interests of the masses anyway.

The US and China will reach a fork in the road over this issue one of these days.