Which preposition to use with ambushment

in Occurrences 1%

Then he knew; saw it all as clearly as though he had witnessed itthe ambushment in the blinding sandstorm; the terror-stricken Waco; the frightened ponies; the lunging and swaying buckboard.

of Occurrences 1%

400 Like as a wily foxe, that, having spide Where on a sunnie banke the lambes doo play, Full closely creeping by the hinder side, Lyes in ambushment of his hoped pray, Ne stirreth limbe, till, seeing readie tide*, 405 He rusheth forth, and snatcheth quite away One of the litle yonglings unawares; So to his worke Aragnoll him prepares.

Which preposition to use with  ambushment