Question:  The Ordnance QF Hotchkiss 6 pounder gun were introduced to defend against watercraft capable of independent operation underwater usually referred to as "boats" rather than what?
Sentence (from "Ordnance QF 15-pounder"): It bore no relation to the BL 15 pounder or BLC 15 pounder, two other guns in British service at the time, other than a common shell.
Relevant evidence: No