From October 1944, the Japanese armed forces organised units whose method was to fly aircraft loaded with explosives directly into Allied ships. Around 4,000 aircrew died in these attacks. The subject is uncomfortable and it is worth setting out plainly what the record shows.
Why it happened when it did
By late 1944 Japan's position had deteriorated in specific ways that shaped the decision.
Pilot quality had collapsed. Japan's pre-war naval aviators had been exceptionally well trained, and most were dead. Replacements received a fraction of the flying hours, and against experienced American pilots in superior aircraft, their survival prospects on conventional missions were already very poor.
Conventional attacks were failing. American carrier task forces had layered defences — radar direction, combat air patrols, and proximity-fuzed anti-aircraft fire that was extremely effective. Conventional bombing and torpedo attacks were achieving little at heavy cost.
Material shortage. Fuel, aircraft and trained crews were all running out.
The calculation made by Vice-Admiral Takijiro Onishi and others was that a pilot who was likely to die achieving nothing might instead die achieving a hit.
What it achieved militarily
The attacks were more effective than conventional methods at that stage of the war, which is the uncomfortable part. Dozens of Allied ships were sunk and hundreds damaged, most heavily at Okinawa in 1945, where sustained mass attacks caused significant US Navy casualties — several thousand sailors killed.
They did not change the outcome. No amount of attrition at that stage could have.
The men
The characterisation of the pilots as uniformly fanatical volunteers does not survive contact with the sources.
Many were university students conscripted late in the war. Letters and diaries left by pilots, which survive in quantity, express a range that includes patriotic conviction, resignation, fear, doubt about the war, and grief at leaving families. Coercion and social pressure within units were significant; "volunteering" in that context was frequently not meaningfully voluntary.
Some pilots returned repeatedly with mechanical faults. Some units' commanders were themselves opposed.
The response
Allied navies adapted: picket destroyers stationed far out to give early warning, heavier close-in anti-aircraft armament, and revised damage control. The picket ships took the heaviest losses precisely because they were the first thing attacking aircraft reached.
How it is remembered
In Japan the subject remains contested, entangled with the wider argument about wartime responsibility and about Yasukuni Shrine. Museums at Chiran and elsewhere preserve pilots' letters, and their presentation has itself been criticised from several directions.
Onishi killed himself the day after Japan's surrender, leaving a note apologising to the dead pilots and their families.
The historical significance for aviation is narrow and grim: it is the first systematic use of a crewed aircraft as a guided weapon, and it is the precedent everyone reached for after September 2001.