23 "probables" for the loss of three fighters. The 454 B-29s that reached Yokohama struck the city's main business district and destroyed of buildings; over 1000 Japanese were killed. Overall, the attacks in May destroyed of buildings, which was equivalent to one-seventh of Japan's total urban area. The Minister of Home Affairs, Iwao Yamazaki, concluded after these raids that Japan's civil defense arrangements were "considered to be futile". On the first day of June, 521 B-29s escorted by 148 P-51s were dispatched in a daylight raid against Osaka. While en route to the city, the Mustangs flew through thick clouds, and 27 of the fighters were destroyed in collisions. Nevertheless, 458 heavy bombers and 27 P-51s reached the city, and the bombardment killed 3,960 Japanese and destroyed of buildings. On 5 June, 473 B-29s struck Kobe by day and destroyed of buildings for the loss of 11 bombers. A force of 409 B-29s attacked Osaka again on 7 June; during this attack, of buildings were burnt out and the Americans did not suffer any losses. Osaka was bombed for the fourth time that month, on 15 June, when 444 B-29s destroyed of the city and another of nearby Amagasaki; 300,000 houses were destroyed in Osaka. This attack marked the end of the first phase of XXI Bomber Command's attack on Japan's cities. During May and June, the bombers had destroyed much of the country's six largest cities, killing between 112,000 and 126,762 people and rendering millions homeless. The widespread destruction and high number of casualties from these raids caused many Japanese to realize that their country's military was no longer able to defend the home islands. American losses were low compared to Japanese casualties; 136 B-29s were downed during the campaign. In Tokyo, Osaka, Nagoya, Yokohama, Kobe, and Kawasaki, "over 126,762 people were killed ... and a million and a half dwellings and over of urban space were destroyed." In Tokyo, Osaka and Nagoya, "the areas leveled (almost ) exceeded the areas destroyed in all German cities by both the American and British air forces (about )." P-51s also conducted a series of independent ground-attack missions against targets in the home islands. The first of these operations took place on 16 April, when 57 P-51s strafed Kanoya Air Field in Kyushu. In operations conducted between 26 April and 22 June, the American fighter pilots claimed the destruction of 64 Japanese