as the sky lightened , grey looked up for a moment from his spot at the top of the cliff , where he was now overseeing the last of the artillery as it was heaved over the edge , and saw the bateaux coming down again like a flock of swallows , they having crossed the river to collect an additional 1,200 troops that wolfe had directed to march to levi on the opposite shore , there to lie hidden in the woods until the highlanders ' expedient should have been proved .