the problem with every modern military is they expect you to do mercenary-level duties but only offer nationalist-level incentives. ww2 made them all fat and spoilt on the idea of men that would wage war for their country for very little pay. then they spent the next 70 years sending those men on offensive operations while keeping the reward dogshit. unless his home was being threatened, you used to have to promise a man the privilege of looting, pillaging, and claiming captured lands for himself to get him to pick up a gun and fight for your flag. that was the standard for almost all recorded history until the world wars.
United Kingdom