Second line doesn't mash too well with the first one. Might just be me, since I can't quite place why, so I'll just leave it at that.
The guy is being a bit dramatic saying "War, you can't describe war." However, being dramatic is fine, I just wonder how it fits in the context of the situation when the other person asked the question. Guess that doesn't really matter, but given the weighty response I do wonder who the two people that are having such a conversation are.
"War is hear the screams..." check this part again, maybe add a 'to' after 'is'.
When I first read "War is getting shot without knowing it" I found it a bit funny. However, with the adrenaline pumping, I realised it probably is a lot more likely to not notice a wound in the moment.
Not sure on the positioning of the exclamation mark. It can work, as it is like the narrator getting more into, then calming don for the final part. However, I still wanted to mention it since it stood out to me.
Also 'they' in the last sentence might be better if replaced with 'you'. This depends on the context of the situation, but as I'm assuming it is narrator talking to the person who asked the question, the 'they' stands out since it isn't clear who 'they' is referring to. Doesn't help that you have been using 'you' exclusively up to this point (inside the narrator dialogue).
You forgot the last closing quotation mark.
Since I haven't experienced war, I guess I can't say if your description is right or wrong, but I will mention that what you described can happen outside a war.
- Dead bodies on the ground.
- Screams of friends as they try to stay alive a few seconds longer.
- Getting shot without realising it.
- Blood pumping.
- Shots firing.
- Trying your hardest to stay alive.
But aside from that, it does paint a pretty strong image of the horrors of war. Also, due to the repetition of 'war', it is pretty clear that you are specifically talking about these things happening during a war.
TL;DR
Looks good to me. Some things stand out a bit, but that is probably because they are written differently to how I would have done it (so it looks off to me despite not actually being wrong). A missing 'to' and closing quotation mark are the only exceptions. Aside from that I'd say swap 'they' in the last sentence with 'you'.
P.S. I should mention that I like the tight focus, you also convey things very quickly here, which is a good skill to have.