Submarine 1400

when "submarine 1400" was mentioned I almost woke up because odd phrases are often a precursor/trigger for my nightmares.. the man sat across the table looked totally broken, when he said it, and there was nothing he could do. So he'd turned to me for help.! I can't remember the actual dream but this '💭Sub1400' surfaced as soon as I woke up. I had no idea they were even a thing until a brief go-ogle came up trumps. I just thought it might mean something to someone and/or.. (what do you think)?