Following the Battle of Bothwell Bridge (22 June 1679), some 1200 prisoners were brought to Edinburgh. Their being too numerous for containment in the prison or castle a makeshift "prison" was formed in a field south of Greyfriars Kirkyard, to hold around 400 not containable elsewhere. This area was conveniently enclosed on two sides by the Flodden Wall and on a third side (the west) by the high enclosing wall of George Heriot's School. The fourth side faced the churchyard and was separated by an easily patrolled and guarded picket fence.