Lord Sovereign
The resident Britbong
Their warrior culture was the problem. Basically, because Bushido viewed suicide as preferable to surrender, any who surrendered were considered completely honorless, so they deserved any treatment they got.
I suppose the words "live to fight another day" didn't mean too much to this lot? Even the Spartans, as big on a "beautiful death" as they were, knew there was a time and a place for it. Ultimately, didn't that doctrine really screw the Japanese over in modern warfare and lead to far higher casualties than needed?