“The Lancastria was the largest loss of life from a single engagement in World War Two”
this is wrong unless author claims he made an error and meant to say something else.
It would have been more correct to say that the sinking of the Lancastria represents the largest loss of life from a British maritime incident.
Possibly, a British military engagement might fit as a descriptor, but I would think there were British battles where more than 4,000 men were killed, maybe even on British soil, with all their civil wars, but I really don’t know.
this is wrong unless author claims he made an error and meant to say something else.
He probably meant to say that it was the largest loss of life by the British.
I thing the Japanese might point out one or two other engagements that resulted in a large loss of life.