and I delivered you out of the hand of the Egyptians, and out of the hand of all who oppressed you, and drove them out from before you, and gave you their land;
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.