Ketteler returned to China in 1899 as Plenipotentiary at Beijing, from where he pointed out in vain the dangerous situation for the Europeans. On 12 June 1900, when the Boxers moved to the inner city and burned down Christian church buildings, Ketteler reacted by ordering German embassy guards to hunt them down. On 18 June, German troops captured a Chinese civilian suspected of being a Boxer in the inner city and took him to the Legation Quarter, where he was detained.