Ground Zero, the 浦上天主堂 Urakami Tenshudō Cathedral of Nagasaki (image source)
“I had already heard about Nagasaki. I had come across it repeatedly in the 'History manual of the Catholic missions' by Giuseppe Schmidlin, three volumes published in Milan in 1929. Nagasaki had produced the first substantial Catholic community in Japan, in the sixteenth century. In Nagasaki, on February 5, 1597, thirty-six martyrs (six missionary Franciscans, three Japanese Jesuits, and twenty-seven laymen) gave their lives for Christ. They were canonized by Pius IX in 1862. When the persecution was resumed in 1637, no fewer than thirty-five thousand Christians were killed. After this, the young community lived in the catacombs, so to speak, but it was not extinguished. In 1865, Fr. Petitjean discovered this 'clandestine Church', which revealed itself to him after it had verified that he was celibate, devoted to Mary, and obedient to the pope of Rome; thus the sacramental life could be resumed as normal. In 1889, complete religious freedom was proclaimed in Japan, and everything began flourishing again. On June 15, 1891, the diocese of Nagasaki was established canonically, and in 1927 it welcomed as its pastor Bishop Hayasaka, whom Pius XI himself had consecrated as the first Japanese bishop. It is from Schmidlin that we learn that in 1929, of the 94,096 Japanese Catholics, fully 63,698 were in Nagasaki.”
Having established this, cardinal Biffi concludes with a disturbing question:
“We can certainly assume that the atomic bombs were not dropped at random. So the question is inevitable: why is it that for the second slaughter, out of all the possibilities, that very city of Japan was chosen where Catholicism, apart from having its most glorious history, was also the most widespread and firmly established?”
Call Me Jorge... would add that the Japanese ended up surrendering under the exact same terms they were suing the United States of America for surrender before the two atomic bombs were dropped. The reason Nagasaki was chosen is because it was the Catholic center of Japan and had the largest cathedral in the Far East. In addition the city of Nagasaki had outlawed freemasonry in 1926. The Allied Powers were afraid that Catholicism would fill the void created by the Japanese Emperor renouncing his divinity, hence it had to be destroyed.