The counterfactual brings the I-400 class into service earlier as large minelayers. Each boat could scatter roughly 150 to 200 mines outside critical ports around the world. Countries with too few minesweepers would face severe disruption. Australia fares comparatively well when the scenario sends only a couple of boats against it, rather than the entire hypothetical force, because the Bathurst class provides substantial clearance capacity. Its crews also understand the danger minefields pose to their merchant-service colleagues and are prepared to undertake the work.
Notable Point · 57:09-58:43
An I-400 minelayer counterfactual tests national mine defenses
Reimagining Japan's large I-400 submarines as long-range minelayers shows how a few minefields could threaten critical ports and why Australia benefited from numerous sweepers.