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

Because they had limited underwater range (like, a couple of days at most) before they had to go to the surface again, and they had to have some sort of protection while they were on the surface – some guns were used to protect against ships, some were used against aircraft. Also, they often targeted relatively unprotected merchant ships (cargo ships), so they could do some damage from the surface without relying solely on torpedoes.

Answer 2

Because they had limited underwater range (like, a couple of days at most) before they had to go to the surface again, and they had to have some sort of protection while they were on the surface – some guns were used to protect against ships, some were used against aircraft. Also, they often targeted relatively unprotected merchant ships (cargo ships), so they could do some damage from the surface without relying solely on torpedoes.