With help from the Americans. Nagasaki was the site of the largest Christian church in the orient, St. Mary's Cathedral. Also had the largest concentration of baptised Christians in all of Japan. (Also the city where the Jesuit missionary, Francis Xavier, established a mission church in 1549.)
The morning of August 9, 1945, a B-29 Superfortress called Bock’s Car, took off from Tinian Island to drop Fat Man on Japan. St. Mary’s Cathedral was one of the landmarks that the Bock’s Car bombardier had been briefed on, and looking through his bomb site over Nagasaki that day, he identified the cathedral and ordered the drop. The bomb detonated only 500m away. Mass was well attended that day. The entire Christian community of Nagasaki was wiped out.
How many Christians died that day? I’d heard of this but not any details. Very sad.