to be expanded to 120 days. In preparation for Operation Olympic, the invasion of southern Kyushu, various figures and organizations made casualty estimates based on the terrain, strength, and disposition of known Japanese forces. However, as reported Japanese strength in the Home Islands continued to climb and Japanese military performance increased, so too did the casualty estimates. In April 1945, the Joint Chiefs of Staff formally adopted a planning paper giving a range of possible casualties based on experience in both Europe and the Pacific. These ranged from 0.42 dead and missing and 2.16 total casualties per 1000 men per day under the "European Experience" to 1.95 dead and missing and 7.45 total casualties per 1000 men per day under the "Pacific Experience." This assessment included neither casualties suffered after the 90-day mark (US planners envisioned switching to the tactical defensive by X+120 ), nor personnel losses at sea from Japanese air attacks. In order to sustain the campaign on Kyushu, planners estimated a replacement stream of 100,000 men per month would be necessary, a figure achievable even after the partial demobilization following the defeat of Germany. As time went on, other US leaders made estimates of their own: In a letter to General Curtis LeMay when LeMay assumed command of the B-29 force on Guam, General Lauris Norstad told LeMay that if an invasion took place, it would cost the US "half a million" dead. In May, Admiral Nimitz's staff estimated 49,000 U.S casualties in the first 30 days of Operation Olympic, including 5,000 at sea. A study done by General MacArthur's staff in June estimated 23,000 US casualties in the first 30 days of Olympic and 125,000 after 120 days, fighting an assumed Japanese force of 300,000 (in actuality some 917,000 Japanese troops were on Kyushu,). When these figures were questioned by General Marshall, MacArthur submitted a revised estimate of 105,000, in part by deducting wounded men able to return to duty. In a conference with President Truman on June 18, Marshall, taking the Battle of Luzon as the best model for Olympic, thought the Americans would suffer 31,000 casualties in the first 30 days and ultimately 20% of Japanese casualties, which he estimated would include the entire Japanese force. This implied a total of 70,000 American casualties in the battle of Kyushu using the June projection of 350,000 Japanese defenders. Admiral Leahy, more impressed by the Battle