All those wretched quarrels, in his humble opinion, stirring up bad blood, from some bump of combativeness or gland of some kind, erroneously supposed to be about a punctilio of honour and a flag,...
1869, R. D. Blackmore, Lorna Doone: A Romance of Exmoor, ch. 71:
Now for these and other things (whereof I could tell a thousand) was the reckoning come that night; and not a line we missed of it; soon as our bad blood was up. I like not to tell of slaughter, though it might be of wolves and tigers; and that was a night of fire and slaughter, and of very long-harboured revenge. Enough that ere the daylight broke upon that wan March morning, the only Doones still left alive were the Counsellor and Carver.
[I]f we dare not search ourselves close enough to discover the low breeding, the bad blood in us, it will one day come out plain as the smitten brand of the forcat.