On this day in 1931, a small charge of dynamite was set off beside the South Manchuria Railway near Mukden. The man who lit it was a Japanese officer, Lieutenant Suemori Kawamoto. The charge was too weak to break the track. A few minutes later a scheduled train ran over the spot and carried on.

I have walked track after far worse than that and found nothing needing more than a look and a note in the book. Here the damage was slight enough to be invisible to the driver, and it was named as an attack by Chinese dissidents and answered with a full invasion. Manchuria was occupied. Five months later it was renamed Manchukuo and governed as a Japanese puppet state. The years that followed cost many thousands of lives in Manchuria and set the pattern for the far wider war to come in China.

There is no railway reason in any of it. The line was intact, the timetable held, the train went through. The rest was decided elsewhere, and paid for by people who had nothing to do with the track.