The agony of choice...I know that feeling.
A similar thing has just happened to one of my skippers, in a Type II NE of Aberdeen in September 1939.
We had one torpedo left (T1) and were perfectly lined up on a fat merchant plodding south towards my cross-hairs when my soundman picks up multiple warship echoes off to the south at about 18k, closing fast.
We surfaced and spun the boat towards the estimated track and were rewarded (teased?) a short while later by the majestic sight of the Home Fleet racing
directly across my bows at a little over 5-6,000m.
They were led by HMS Hood - the first time I have ever seen her in the flesh in eight years of playing this game - and she was followed by a Renown class, an Illustrious class, both the Nelsons, three Southamptons and about 8 destroyers, all doing 25kts and not keeping a very good lookout.
I was in a perfect shooting position and still had the large merchant in sight at 7,000m astern of me!
So, a high probability of success against a large merchant or a slim chance of glory...?
"Target leading warship - LOS!"
The torpedo hissed away at 40kts and I turned the boat and made off on the surface at high speed into the night.
Dunno what happened to the torpedo but it didn't go bang (mag, 11.6m, shade over 5,300m when fired) and the warships continued merrily on their way, as did one lucky merchant.
All I had to show for the juiciest encounter I have ever had with SH/GWX was an 'enemy contact report' which BdU kindly acknowledged about five hours later.
Oh well, maybe next time. If anyone would like the position, course and time of this contact, pm me, if GWX would replicate it.
KH