Douglas Harper's Etymology Dictionary
Usage examples of "pre-engage".
They neither of them had any idea of my heart having been pre-engaged, and the strangeness of my manner was ascribed by Bramble to my feelings towards Bessy.
He acts also contrary to his trust when he employs the force, treasure, and offices of the society to corrupt the representatives and gain them to his purposes, when he openly pre-engages the electors, and prescribes, to their choice, such whom he has, by solicitation, threats, promises, or otherwise, won to his designs, and employs them to bring in such who have promised beforehand what to vote and what to enact.