Torpedoes as a capital ship's finishing weapon

What was the intended purpose of torpedoes on large warships?

They could finish damaged opponents and provide a backup strike weapon when guns were inadequate or the ship was itself damaged.

A battle might leave a ship with only secondary armament facing a crippled enemy hull that still needs sinking. A torpedo could finish the disabled target when the remaining guns were inadequate. The same weapon gave a badly damaged capital ship one more strike if an opponent closed for the kill. Torpedoes therefore served as endgame and emergency weapons alongside their more familiar offensive uses, and the Royal Navy did employ them from large ships on occasion.