Q&A ยท 55:14-56:54

Why invading Oahu required far more than the carrier raid

Two Army divisions, coastal artillery, Marine defense battalions, and engineers made seizure of Pearl Harbor a major amphibious undertaking.

Question

Could Japan have landed Marines and engineers to seize or demolish Pearl Harbor's facilities?

Short answer

Only with a much larger amphibious force, because Oahu already held two Army divisions, coastal artillery, Marine defense battalions, and engineers.

Notes

The Hawaiian garrison included the 24th and 25th Infantry Divisions, although both contained Hawaiian Territorial Guard regiments and were not presented as perfectly formed combat divisions. Oahu also had extensive coastal artillery. Three Marine defense battalions and an engineering battalion added further infantry, antiaircraft, and base-defense capacity. The rough estimate given here puts these forces at about seven brigade equivalents. Japan would therefore need a large landing force and substantial logistics to seize or hold the island, quite apart from the carrier strike needed to suppress the fleet and airfields.