I also just happened to encounter my first battlship while intercepting a convoy today.
Also a Revenge class. My eyes just about popped out of my head when I first spied her through the periscope. Unfortunately I was too far back and at an oblique angle with escorts breathing down my neck to have a go.
I backed out and shadowed the convoy for about 3 hours, finally setting up an intercept. Somehow I pulled it off like it was text book.. Came in behind the lead escort and crawled low and slow right into the middle of the convoy undetected. Anyone notice the convoy is super wide in formation when a battleship is in the middle?
Set up dead perpendicular to the Revenge at about 800 meters. God this game can put you on the edge of your seat - specially as I was a battleship "virgin" - I think I checked my torp settings about 30 times in the last 2 minutes before firing :rotfl:
3 eel salvo, all magnetics for under keel - I was hoping to get a spectacular munitions or fuel explosion, didnt get it

all eels impacted and she slid down gracefully to her grave. New single greatest moment for me in SH3/GWX