Naval Historywith Dr. Alex

Q&A · 2:45:44-2:46:21

Could Japan expand submarine construction in wartime?

Japan's need for more submarines runs into the same yard-capacity constraint that shaped Yonai's opposition to the Yamato program.

Imperial Japanese NavyNaval Industrial BaseShipyardsSubmarinesYamato Class Battleships
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Question

Could Japan increase submarine construction once the Pacific war exposed a greater need for them?

Short answer

Not quickly: limited shipyard capacity and the Yamato program left too little industrial flexibility for a major wartime expansion.

Notes

Japan could not answer wartime demand simply by ordering many more submarines. Its maritime industrial base lacked spare yards and supporting capacity, especially while the Yamato class absorbed exceptional resources. The same bottleneck also made it difficult to build the additional infrastructure needed for faster output. Yonai's criticism was therefore about opportunity cost: a few immense battleships restricted the navy's ability to adapt its force mix after war began.