On 9 August 1945, a six-strong squadron of the United States Air Force set off for Japan carrying a plutonium bomb almost twice as powerful as the enriched-uranium bomb dropped on Hiroshima three days earlier. Their intended target was the city of Kokura, with its major munitions plants. However, when they arrived, heavy cloud cover forced the pilots to revert to their secondary target, Nagasaki. But cloud cover was heavy there too, and with fuel running critically low the bomber Bockscar dropped its bomb inland, nearly two miles away from the planned target site. As a result, the twenty-two-kiloton explosion was not quite as devastating as the direct hit at Hiroshima. The brunt was born by the Urakami valley, and the hills surrounding the valley gave some protection to the rest of the city. Around a third of the city's people, perhaps as many as 80,000, died in or shortly after the bombing.

So when they bombed the Urakami valley, then, the US Air Force did not deliberately target the single most important centre of Japan's tiny Christian minority, the site of what was at the time the largest Christian cathedral in East Asia. The facts that more than two-thirds of Nagasaki's Catholic population were killed; that over a tenth of all the casualties were Christians; that in one day, the US Air Force had killed more Japanese Catholics than had been executed in two and a half centuries of persecution – all of these things were, in one sense, unintended.

But how were the surviving Japanese Catholics to make sense of this fresh calamity, one shared with the nation but also peculiarly their own? As Gwyn McClelland's sombre book lays out for us, they have found themselves compelled to treat this most recent catastrophe as a continuity of their community's centuries-long sufferings. The bombing has become known amongst Nagasaki's Catholics as the ‘fifth persecution’, the first four having been inflicted by the Tokugawa shogunate. The Tokugawa regime's rhetoric proclaimed the ‘crushing’ of Christianity; the bomb made that metaphor a reality.

McClelland's book is built around the testimony of a series of Japanese Catholic survivors, witnesses and interpreters of the bombing. Looming over them all is the Catholic convert and doctor Nagai Takashi, whose wife died in the actual bombing and who himself died of radiation-related illness in 1951. For him, Nagasaki, and in particular Urakami, was again become a field of martyrs. Seeing the community's sufferings in this way gave them a very particular meaning. In this light, it was critical that the bombing of Nagasaki was the very last horror of the war, the place where the worldwide killing finally came to an end. In 1948 Nagai wrote:

His work became a bestseller throughout Japan, far beyond the Catholic community. The notion of Nagasaki as a burned offering, mutely sacrificing itself for peace, resonated powerfully with the whole country's postwar trauma. It gave a duality to Japan's response to the atomic bombs: proverbially, it is said, ‘Hiroshima rages, Nagasaki prays’. The ruins of Urakami's cathedral became a widely recognised symbol of the nation's suffering under the atomic bombs. In the rebuilt cathedral, the now-iconic images of the ruins are compelling recalled in modern stained glass (reproduced here, though sadly not in colour: images can easily be found online), and blast-damaged statues still survive and are preserved in its grounds. The human martyrs of 1945 were vaporised: their cathedral has become their relic.

Yet, as McClelland explains, some Japanese Catholics have begun to push back against these silent, passive understandings. The community suffered significant apostasy amongst the survivors in the years afterwards; and subsequent generations of survivors have found different voices, from lament to protest. The horrors of the bombing – in particular, the way that blast-survivors were consumed by thirst, cried out for water, but all too often then died agonisingly after drinking, whether because of their internal injuries or because the water itself was lethally irradiated –have been taken up as symbols not only of suffering but of the cry against injustice. The biblical figure of Job has become widely cited as a paradigm for the community, a community which has become able to assert that it has suffered and continues to suffer persecution and discrimination in its own country as well as having been nearly annihilated by its supposed foreign friends.

American narratives justifying the bombing, official Catholic silence on the issue, the stirrings of Japanese nationalism: this community, tiny as it is, has set itself against them all. All they have is moral authority and some very dearly bought theological insight. McClelland's book does them service. His book gives us voices that many of us find too painful to hear, talking with unsettling clarity about events we would prefer to forget.