The QF 4.7 inch Gun Mark V originated as a 4.7 in (120 mm) 45-calibre naval gun designed by the Elswick Ordnance Company for export customers and known as the Pattern Y.

[1] In World War I the UK acquired 620 [3] of a version manufactured in Japan, and mounted them as anti-submarine guns on merchant ships and troop ships, under the designation Mark V*.

On 10 March 1917 the crew of a single gun on the refrigerated cargo liner Otaki fought a notable action against the heavily-armed German commerce raider SMS Möwe.

They managed to set the Möwe on fire and inflicted significant damage before the Otaki was sunk.

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