If it doesn't relate to a historic event of sacking and/or vandalizing (like General Sherman's deeds), it looks pretty much a hybrid between "cumplir a rajatabla" and "someter a sangre y fuego"; the kind of melange people make in everyday speech or Internetish and later label as "common" expressions.
cumplir a rajatabla = do or follow to the letter, without compassion nor room for flexibility
someter a sangre y fuego = crush by fire and sword
So it could be:
El rey le ordenó someter a los rebeldes, lo que cumplió a sangre y fuego.
or most probably a portmanteau, disposable, informal phrase:
"y no aflojó y lo cumplió a sangre y fuego" = indeed he did, that relentless bastard
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