What kind of hymn/song would a soldier sing before going on to the battlefield?

I am writing a story. I would really like it if I could have a scene where one of the soldiers starts humming or singing an old tune as they wait to go out on a battlefield. I want something kind of slow and haunting, maybe something more like a song that's sung for the dead, or something similar. Links to recordings would be appreciated, but any help is good help! I am not particular about the religious origin or anything like that.What kind of hymn/song would a soldier sing before going on to the battlefield?
I'd say Nutshell - Alice in Chains.

it's soft, but the lyrics are warlike, and it's got a very nice humming sound, if that makes sense.

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