The siege of Baghdad (May-9 July 1401) was one of Tamerlane's most destructive victories, and saw the city virtually destroyed after it was taken by storm at the end of a forty day long siege. After the capture of the city, 20,000 of its citizens were massacred. Timur ordered that every soldier should return with at least two severed human heads to show him. When they ran out of men to kill, many warriors killed prisoners captured earlier in the campaign, and when they ran out of prisoners to kill, many resorted to beheading their own wives.