E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Dun in the Mire.
To draw Dun out of the mire. To lend a helping hand to one in distress. The allusion is to an English game, explained by Mr. Gifford in his edition of Ben Jonson, vii. 283. A log of wood is brought into a room. The log, called Dun, is supposed to have fallen into the mire, and the players are to pull him out. Every player does all he can to obstruct the others, and as often as possible the log is made to fall on someones toes. Constant allusion is made to this game.
Sires, what? Dun is in the mire.Chaucer: Protogue to Maunciples Tale.