Duty to retreat 'to the wall'
The duty to retreat, if a safe retreat is available, before using deadly force in self-defense is sometimes called the duty to "retreat to the wall." I had always thought this originated as a metaphor—you have to retreat until safe retreat is no longer possible—but it turns out that the phrase is generally traced back to a 1329/30 case that had an actual wall. Here's the English translation, from 97 Selden Society 164 (some emphasis and some paragraph breaks added):
Simon Osbern was arrested for killing Nicholas fitz Simon of Gildesburgh of Sprotton, who was killed at Haselbech on 27 July 1328. Simon was indicted before the coroner. He now appears in court and, upon being asked how he wishes to clear himself of the aforesaid homicide, denies all felony and homicide and everything that is against the peace etc., and to establish that he is not guilty thereof puts himself for better or worse upon the country.
The jurors of the hundred of Rothwell and of the honour of Berkhampstead, chosen and tried for this case, say upon their oath that on the aforesaid day in the aforesaid year the aforesaid Simon and Nicholas quarrelled on the way to the tavern at the house of James Anneys in Haselbech. A fight broke out between them and Nicholas struck Simon in the head with an ashen staff and knocked him down.
Simon got up and straightway fled as best he could. Nicholas kept on pursuing him with the staff, intending to kill him. He chased him to a wall between two houses, where there was no way at all for Simon to go on. When Simon saw that Nicholas would kill him with that staff and that he must defend himself or die, he took a small pole-axe and struck back at Nicholas and hit him in the head, so that he died on the spot. Immediately afterwards Simon fled as best he could. Wherefore they say that Simon killed Nicholas in self-defence and not in felony or malice aforethought. And they say expressly that if Simon had not so defended himself he could not have avoided being killed.
Simon is therefore remanded to prison in the keeping of Thomas Wake the sheriff to await the king's grace. His chattels are confiscated for flight. His chattels are worth 29s. 3d., with which sum the sheriff is charged.
Later Simon appeared and proffered a charter of the king which stated that the king pardoned Simon the suit of his peace which pertained to him for the aforesaid homicide. Dated at Kenilworth on 11 December 1329. The aforesaid sheriff is therefore commanded to deliver Simon from prison.
Note that this result—the defendant wasn't acquitted as such, but was rather pardoned by the king as a result of the jury's self-defense verdict—was indeed the norm in early English law.
Thanks to my brother Sasha for tracking down the English translation.