Rumbold was an honorary
attaché at
The Hague (1889–1890), where his father was ambassador. In 1891, he passed the first of the required examinations and entered the Diplomatic Service. After the war, he was appointed
ambassador to Poland in 1919, The following year, he became the
High Commissioner to Constantinople during which he signed the
Lausanne Treaty on behalf of the
British Empire. He then became
ambassador to Madrid from 1924 to 1928. Rumbold was appointed to his last position as
ambassador to Berlin in 1928. He supported appeasing
Heinrich Brüning's government in the hope of staving off German
nationalist parties such as
Adolf Hitler's
Nazi Party. Once Hitler came to power in 1933, Rumbold was deeply unsettled by the Nazi regime and produced a succession of despatches critical of the Nazis. On 26 April 1933 Rumbold sent to the
Foreign Office his valedictory despatch in which he gave an unvarnished view of Hitler, the Nazis and their ambitions: [Hitler] starts with the assumption that man is a fighting animal; therefore the nation is a fighting unit, being a community of fighters.... A country or race which ceases to fight is doomed.... Pacifism is the deadliest sin.... Intelligence is of secondary importance.... Will and determination are of the higher worth. Only brute force can ensure survival of the race. The new Reich must gather within its fold all the scattered
German elements in Europe.... What Germany needs is an increase in territory... [to Hitler] the idea that there is something reprehensible in chauvinism is entirely mistaken... the climax of education is military service [for youths] educated to the maximum of aggressiveness.... It is the duty of the government to implant in the people feeling of manly courage and passionate hatred.... Intellectualism is undesirable...It is objectionable to preach international understanding... [he] has spoken with derision of such delusive documents as peace-pacts and such delusive ideas as the spirit of Locarno. Rumbold concluded by giving stark warnings for the future of international relations: ...it would be misleading to base any hopes on a return to sanity...[the German government is encouraging an attitude of mind]...which can only end in one way.... I have the impression that the persons directing the policy of the Hitler government are not normal. Sir
John Simon, the
Foreign Secretary, found Rumbold's descriptions to be "definitely disquieting". After Rumbold's death,
Lord Vansittart said of him that "little escaped him, and his warnings [about Nazi Germany] were clearer than anything that we got later".
Walter Laqueur concurred by claiming that Rumbold's "prophetic" insights explained the Third Reich better than the expert opinions that were later issued from the
OSS. ==Honours==