Naval Historywith Dr. Alex

Q&A · 6:34:50-6:35:55

Early I-400 operations would pull American escorts home

Japanese submarine-aircraft attacks on the US coast would create limited physical damage but strong political pressure for coastal anti-submarine defenses.

Anti-Submarine WarfareI-400 Class SubmarinesImperial Japanese NavySubmarine AircraftUS Navy
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Question

What if Japan had I-400 submarine squadrons ready at the start of the Pacific War?

Short answer

They could raid the US coast and force a costly defensive diversion, but American mass production of patrol craft and escorts would limit their strategic effect.

Notes

Squadrons of I-400-type submarines available in 1941 could launch aircraft against symbolic or vulnerable targets on the American coast. The direct destructive effect would probably remain modest compared with conventional carrier operations. Political reaction would nevertheless force the United States to divert destroyers, patrol aircraft, and other anti-submarine assets to home waters. American industry could answer with mass-produced escorts, including Flower-like corvettes, turning the campaign into an expensive diversion for Japan.