His nephew, the diplomat Wilhelm Freiherr von Ketteler, was murdered by the Sicherheitsdienst des Reichsführers SS (SD) in Vienna in 1938 for his opposition to Hitler.

[2] Following his graduation in Münster and Coesfeld in 1873, Ketteler entered the Prussian Army and served in it until he was appointed to join the Imperial German diplomatic corps in 1882.

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.

[citation needed] On 17 June, the Chinese Muslim Gansu Braves mounted an assault on Ketteler and his German Marines at the Legations.

[1][dubious – discuss] In response, thousands of Chinese Muslim Gansu Braves under General Dong Fuxiang of the Imperial Army and Boxers went on a riot.

[1] At 8.00 a.m. on 20 June, Ketteler, together with his interpreter and other associates, headed for the Zongli Yamen (the Ministry of Foreign Affairs) accompanied by armed escorts.

At the western end of Xizongbu Hutong, only one block away from the ministry, the party was intercepted by a cart with what appeared to be Chinese Imperial lancers,[9] though another source states they were Manchu Hushenying bannerman.

[14] Ketteler was succeeded by Alfons Mumm von Schwarzenstein as ambassador of the German Empire in Beijing,[15] who signed the Boxer Protocol on behalf of Germany.

[26] After returning to her family in America after his death, his widow, who never remarried, later lived at a villa in Florence, Italy, before leaving shortly before World War II.