So I am looking for the 1650 gunboat rules, specifically I never heard of a rule that a game ends at turn 50.
It’s on page 6 of 12 of the Standard Gunboat Rules (which are on the Middle Earth Website under “variants” and “downloadable varients - detailed rules.” I just checked again.
Frankly, I had completely forgotten about the 50-turn rule until it happened. I had this great scheme of conquest that was just starting to unfold, too!
Bradford (The Fire King in game 55).