For over a century England’s judicial system decided land disputes by ordering disputants’ legal representatives to bludgeon one another before an arena of spectating citizens. The victor won the property right for his principal. The vanquished lost his cause and, if he were unlucky, his life. People called these combats trials by battle. This paper investigates the law and economics of trial by battle. In a feudal world where high transaction costs confounded the Coase theorem, I argue that trial by battle allocated disputed property rights efficiently. It did this by allocating contested property to the higher bidder in an all-pay auction. Trial by battle’s “auctions” permitted rent seeking. But they encouraged less rent seeking than the obvious alternative: a first-price ascending-bid auction.