BLENCH, verb intransitive [This evidently is the blanch of Bacon [see Blanch.] and perhaps the modern flinch.]
To shrink; to start back to give way.
BLENCH, verb transitive To hinder or obstruct, says Johnson. But the etymology explains the passage he cites in a different manner. 'The rebels carried great trusses of hay before them, to blench the defendants' fight.' That is, to render the combat blank; to render it ineffectual; to break the force of the attack; to deaden the shot.
BLENCH, noun A start.