behold, I will put a fleece of wool on the threshing floor; if there be dew on the fleece only, and it be dry on all the ground, then shall I know that you will save Israel by my hand, as you have spoken.
So here was Gideon hiding from the Midianites as he was threshing the wheat because if the Midianites had caught him they'd take the wheat. And so he was out by the winepress threshing wheat and here was an angel sitting under an oak tree.