neilmac Dec 14, 2019:

@phil I'm unable to post an 'agree' below due to the asker's restrictions, so here it is :-)

Wendy Streitparth Dec 13, 2019:

Really that should be another question. You could say the shortest-serving officer' or the 'most recently appointed officer'.

Marioly Sanchez (asker) Dec 13, 2019:

Yes, I only used the captain rank as an example. The text is rather general. It just says "oficial más antiguo u oficial menos antiguo" and doesn't state the ranks. There are different types of seniority (?): At institutional, unit and rank levels, for instance. So an officer could be the longest-serving officer within the rank of captain, and be promoted to major and become "el oficial menos antiguo" in the rank of major. Bad part is I can't come up with any translation for "oficial menos antiguo". Any ideas?

Wendy Streitparth Dec 13, 2019:

I think you would need to say "the longest-serving" + rank, because the longest-serving officer might have spent many years in a lower rank and only recently been promoted to captain but still be the "longest-serving officer" because the other captains climbed the ranks much faster but have been captains longer.
If you understand what I mean!