Naval Historywith Dr. Alex

Q&A · 4:27:16-4:28:34

The 16-inch shells adapted into Pearl Harbor bombs

Japan converted 16-inch naval shells rather than nonexistent 15-inch ammunition, prompting a related counterfactual about British G3 construction.

Armour Piercing BombsAttack On Pearl HarborG3 Class BattlecruisersImperial Japanese NavyKongo Class Battlecruisers
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Question

Were the Japanese battleship shells converted into Pearl Harbor bombs 15-inch or 16-inch weapons?

Short answer

They were 16-inch shells; Japan did not field a 15-inch battleship gun from which to take them.

Notes

The panel identifies the heavy armor-piercing bombs used at Pearl Harbor as conversions from 16-inch shells. Japan had 14- and 16-inch battleship weapons rather than a 15-inch service caliber, so a 15-inch origin does not fit the fleet's ammunition. The exchange then tests what 15-inch guns on the Kongo class would imply for the earlier naval balance. British planners would be far less willing to abandon the G3 battlecruisers before negotiating a treaty if Japanese fast capital ships already carried weapons of that size. The short correction therefore connects ordnance identification with the competitive logic behind interwar capital-ship programs.