I haven't read it, but if it involves casualty rates for the US military which make the D-Day invasion look like a minor traffic accident, it's probably not far off.

The expected casualty rate was horrendous, and based upon the ferocity of the Okinawa invasion. In the planning for Operation Olympic, entire divisions are not accounted for after the first couple of days, they were expected to have been utterly destroyed. An article from Stars and Stripes dated 2010 confirms the possibility that a soldier awarded a Purple Heart could receive one made in 1945 in expectation of the amount of casualties which would be incurred.They expected up to 1million casualties. For whatever reason, the last solid figure reported by the Defense Logistics Agency dated to 1985, there were still 120,000 unawareded medals.