The multinational force behind Operation Downfall

Would Commonwealth troops have made up about a quarter of the forces for an invasion of Japan?

The invasion would require a large Commonwealth contingent, Soviet participation, and later follow-on waves beyond the first landing.

One estimate put Commonwealth forces at roughly a quarter of the troops for an invasion of Japan. Soviet troops and later follow-on forces would enlarge the coalition beyond the first wave. The campaign was expected to be extremely bloody. Concern for whether Japan's population could survive the projected plans conveys the operation's scale.