The Probert Encyclopaedia of Ships

UNBROKEN

HMS Unbroken was a British Ursula Class submarine of 540 tons displacement launched in the early 1940s. She was armed with one small gun and six 21-inch torpedo tubes in the bow. She had a top speed of 11.25 knots surfaced and 10 knots submerged and carried a complement of 27.
Research Unbroken