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I think for the term (peers) هم درجه ای ها or even همتا renders the meaning better, because it's a military text while refering to this fact that these people have the same rank or position in the military system.
equivalents such as (همکاران، دوستان،هم سن و سالان، دیگران) are very general. (for example هم سن و سال) I mean two people may be of the same age but not of the same rank.(or هم کار) all of the people may be functioning in the same system but in different ranks. none of the equivalents mentioned in the parenthesis gives the idea of the people who share the same rank or position,while here rank or position is very important.

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