Eli5: Why did early Military/Naval submarines have deck guns?

Question

Eli5: Why did early Military/Naval submarines have deck guns?

In: 2

Answer 1

Torpedoes are pretty large, so small early submarines had a limited supply. U-Boats at the beginning of WW1 only had a half dozen torpedoes on board, and the workhorse of the German WW2 fleet could only carry 14. Shells for a deck gun are much more compact, so using that whenever possible allowed for longer cruises and more sunken ships before heading back for resupply.

Answer 2

Torpedoes are pretty large, so small early submarines had a limited supply. U-Boats at the beginning of WW1 only had a half dozen torpedoes on board, and the workhorse of the German WW2 fleet could only carry 14. Shells for a deck gun are much more compact, so using that whenever possible allowed for longer cruises and more sunken ships before heading back for resupply.