> During war-time, I would assume the body's of your enemy would be plentiful.

In fact, when for instance Taliban or Daesh look at things, the enemy bodies are not plentiful at all. I think it is extremely rare for an American, British or NATO partner soldier's body to fall in their hands. The Western losses in those wars are very small by historical standards, almost negligible, and evacuation is extremely efficient.

For instance, take the current Afghanistan war. Wikipedia: "As of October 1, 2015, there have been 2,326 U.S. military deaths in the War in Afghanistan. 1,856 of these deaths have been the result of hostile action."

1,856 casualties from enemy action in about 15 years. That is about the same number of casualties as Omaha Beach took in a single day. It's half of what my father's brigade inflicted in a single day against one single Russian infantry regiment in February 1942. It is one thousandth of what German Feldheer suffered in all of WWII, and one five-thousandth of what the Soviet army suffered in their "great patriotic war" during four years.

Casualty numbers in modern wars where Western troops attend are very small, when compared to historical wars.

The current Syrian civil war is then another matter. Its casualty numbers are not big when compared to WWII, but they are much bigger than Afghan or Iraq wars.

[My previous comment was of course wrong in the sense that US, UK and NATO troops are not the only enemies that Taleban or Daesh have. Other combatants - be it the Afghan army or Kurdish troops - that fight them do suffer more casualties. But also the propaganda value of those other enemies, when dead or alive at their hands, is much smaller.]

It's also a way of telling troops that if you get stranded, we'll even come and rescue corpses, so never give up hope.

It's mostly a propaganda things, but in special operations (from were many things in the military gets appropriated) it has a purpose. Which isn't about "comfort" as some has suggested, but rather about accountability. If you don't speak up about something and someone gets in trouble, you will have to go and get them. Which works both ways. But also if you make a mess, your friends will have to risk their lives (more than usual) to come get you and that is a horrible rather than comforting thought.

It's basically "we are all in the same boat", which is true (sometimes literally) when you're engaged in high-risk activities. Note that high-risk in this case doesn't mean that you might get killed, but that there is a low margin for error leading to catastrophic failure. Special operations are not about being a fair fight, it's about using your advantage and once you loose that you're often in big trouble.

Say you're doing recon on enemy territory and calling in airstrikes. You're a small mobile force that is hard to find having disproportionate impact on the battle, which is good. Then someone drop a glove or breaks his leg or anything else that compromises the mission and now you're just a small force soon to be a disproportionate loss, which is bad.

It's probably not a legitimate concern between two advanced regular militaries who follow the laws of war and would bury your dead with respect if they can't actually return them to you, but if you left a uniformed western body where ISIS can get it then I'm sure that would end very nastily indeed, with photos on social media and so on. Think of the military contractors burned and hanged on that bridge in Iraq.

'No man left behind' is practical, both for the propaganda reason above and unit morale, not about showing off. But like most things in military life I never heard anyone ever bombast about 'no man left behind' like they do in the movies.

"hey, soldier, go on this risk thing because everybody will be looking for you. Yes, we are a team!"