Green’s Dictionary of Slang

quake breach n.

a coward.

1608		J. Withals Dictionarie in Eng. and Latine 338: Excors, a hartlesse, a faint-hearted fellow, a quake-breech, without boldnes, spirit, wit, a sot.
a.1647		Rowley & Middleton Wit at Severall Weapons I i: And not stand putting in one foot, and shiver, / And then draw t’other after, like a quake-buttock.