Sub-Lieutenant

Sub-Lieutenant is a military rank. It is normally a junior officer rank. In many navies, a sub-lieutenant is a naval commissioned or subordinate officer, ranking below a Lieutenant. In the Royal Navy the rank of sub-lieutenant corresponds with, but is immediately junior to, the rank of Lieutenant in the British Army and of Flying Officer in the Royal Air Force. An RN sub-lieutenant ranks above an Army Second Lieutenant or an RAF Pilot Officer.
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