Then the men of the city said to Joash, Bring out your son, that he may die, because he has broken down the altar of Baal, and because he has cut down the Asherah that was by it.
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.