Between the wars, Mason-MacFarlane attended the
Staff College, Quetta from 1919 to 1920. At Quetta, his evaluation upon graduation declared his ability as "above that of any of his fellow students", though his judgement was described as only "fairly good ... rather immature and lacking balance". Afterwards, he served on regimental duties, before attending the
Imperial Defence College, a prestigious posting for the most promising officers, in 1935. In 1931, after spending most of the preceding ten years in
British India, he was appointed military attaché to
Hungary,
Austria and Switzerland. The director of
M3, the intelligence section of the
War Office dealing with Central Europe wrote in an evaluation of Mason-MacFarlane: "He combines a first-class brain with a remarkable flair for intelligence work. He has a keen sense of humour and is an excellent linguist. Full of mental and physical energy and with great initiative...he should go far". A lover of fast cars, he was badly injured in a car crash in 1933 that left him with spinal pain for the rest of his life. In 1934, Mason-MacFarlane returned to Great Britain. Mason-MacFarlane served as Britain's
military attaché to
Berlin prior to the
Second World War, under the ambassador Sir
Nevile Henderson starting in January 1938. Additionally he served as military attaché to Hungary, Austria, Switzerland and Denmark. In his favourite Ford V-8 coupe, Mason-MacFarlane went out to personally observe the
Anschluss after the
Oberkommando der Wehrmacht denied to him that it was happening and to investigate the German-Czechoslovak border region during the
May Crisis. His reports during the May Crisis that he found no evidence of an imminent German invasion of Czechoslovakia did much to cool down the heated atmosphere during the weekend of 20–22 May 1938. "Mason-Mac" as he was known to his colleagues in the
embassy in Berlin was viewed as an eccentric with some like Sir
Walford Selby, the ambassador in
Vienna, praising him for his "consistently good advice" while others like Sir
Alexander Cadogan, the Permanent Undersecretary at the Foreign Office, regarded him as reckless and too easily excited. The British historian
D. C. Watt called Mason-MacFarlane a "courageous eccentric" who very much wanted to assassinate Hitler. On 27 July 1938, Mason-MacFarlane reported to Henderson that the Wehrmacht was preparing for a war against Czechoslovakia, stating in a report that the
German Army generals were "seeing to it that if the emergency arises their preparations shall not be found wanting". Henderson passed on Mason-MacFarlane's report to London, but stated he did not believe that Hitler was preparing to invade Czechoslovakia. Halifax wanted Mason-MacFarlane to take back a personal message to Hitler, a course of action which he rejected as a "waste of time". Upon his report to Berlin, on 8 August 1938, Mason-MacFarlane met Victor von Koerber, a retired officer and Berlin correspondent of the
Wiener Journal, who had excellent contacts with the German General Staff. For the first time, Mason-MacFarlane learned that Hitler planned to invade Czechoslovakia on 1 October 1938 and of his belief that neither Britain nor France would do anything in the event of the invasion. In late August, Mason-MacFarlane submitted a report to Henderson declaring that if Britain made an alliance with Czechoslovakia that this offered 'an outside possibility that we might avert or at any rate postpone catastrophe". On 23 September 1938, the outcome of the Chamberlain-Hitler summit at
Bad Godesberg ended with Hitler rejecting the Anglo-French plan for the cession of the Sudetenland as taking too long and demanded the region "
go home to the Reich" immediately, a demand that Chamberlain in turn rejected. In the tense atmosphere with Germany and Britain on the verge of war, Wilson was left behind by Chamberlain in Berlin to try to keep the lines of communication open. Mason-MacFarlane was sent by Henderson and Wilson to deliver a message to text of Hitler's Bad Godesberg ultimatum to
Prague but the German-Czechoslovak border was closed, forcing him to cross the frontier by a forest path. While crossing the frontier, he was caught up in the
barbed wire, and a nervous young
Czechoslovak Army soldier helped untangle him instead of challenging him, an experience that left with the conviction that Czech morale was poor. During his journey through the Sudetenland, he had to dodge bullets as he witnessed fighting between the Nazi
Sudetendeutsches Freikorps and the Czechoslovak police and army. Upon reaching Prague and after delivering the message to President Beneš, Mason-MacFarlane telegraphed a cable to London stating based upon what he had seen in the Sudetenland that the Czechoslovak Army was suffering from low morale and would swiftly collapse if Germany invaded. Colonel H.C.T Stronge, the British military attache in Prague very strongly disagreed with Mason-MacFarlane's assessment of the Czechoslovak Army. Wilson saw Mason-MacFarlane's report predicating that Czechoslovakia would last a few days against the Wehrmacht as a reason not to go to war with Germany and circulated it widely through the corridors of Whitehall. From Berlin, Wilson telegraphed Chamberlain: "Military attache has just returned from Czechoslovakia and is convinced that resistance will prove feeble. This must be known to the French too and to the Czech General Staff as it is clearly known here". When Wilson returned to London on 27 September 1938, he took Mason-MacFarlane with him, straight to a cabinet meeting at
10 Downing Street. Mason-MacFarlane told the cabinet: "It would be very rash to base any policy on the assumption that the Czechs would fight like tigers". Cadogan wrote in his diary about the impact of Mason-MacFarlane's presentation to the cabinet: "Unfortunately Mason-Macfarlane (MA in Berlin) also here and he painted a gloomy picture of Czech morale. What does he know about it? Also meeting with Chiefs of Staff who were called in. Not very reassuring...all this produced a glacial period in Ministerial feet". General Sir
Henry Pownall, the Director of Military Operations and Intelligence wrote in his diary: "We were much influenced by the views of Mason-Macfarlane who flew over from Berlin that afternoon [27 September] – he has done noble work." On 30 September 1938, the
Munich Agreement put an end to the crisis which had pushed Europe to the brink of war. After the Munich Agreement, Mason-MacFarlane served as part of the Anglo-German-French-Italian commission which had the duty of deciding how much of the Sudetenland would go to Germany. From October 1938 to February 1939, Henderson was in London being treated for the cancer which was to kill him in 1953. The chargé d'affaires, Sir
George Ogilvie-Forbes, took over the British embassy in Berlin during this time. He, too, disagreed with Henderson's views of the Nazi regime, andallying with Mason-MacFarlane used his position to "educate" the British cabinet about Germany. On the night of 9 November 1938, Mason-MacFarlane witnessed the
Kristallnacht ("night of broken glass") pogrom in Berlin, where the homes and businesses of Jews were looted and vandalised while Jews were beaten up and sometimes killed.
Kristallnacht repulsed and disgusted him, adding to his dislike of the Nazi regime. Mason-MacFarlane stated the German economy was on "full throttle" for war and Hitler would probably invade an Eastern European state in 1939, through he also stated there was a strong possibility of Hitler attacking a Western European state. The possibility of Hitler attacking the
Low Countries and/or
France that Mason-MacFarlane had warned about had more impact on the British cabinet than did his warnings of aggression in Eastern Europe, and changed Britain's policies towards France. Henderson upon his return to the British Embassy on 13 February 1939 stated that henceforward all dispatches from Berlin had to conform to his views. Mason-MacFarlane added greatly to Colvin's credibility when he endorsed his reports, saying Colvin was a reliable source of information about Germany. In a letter to his sister, Chamberlain wrote that it was the "Colvin report" together with information from other sources that led him to agree to Lord Halifax's idea of the "guarantee" of Poland. Mason-MacFarlane proposed the
assassination of
Adolf Hitler, an offer turned down by his superiors. Mason-MacFarlane's plan was to shoot Hitler while he was on a stand reviewing the Wehrmacht for his 50th birthday celebrations on 20 April 1939; Mason-MacFarlane's apartment window was no more than 100 yards from the reviewing stand.
Lord Halifax, the Foreign Secretary, said "We have not reached that stage... when we have to use assassination as a substitute for diplomacy." Hitler for his part regarded Mason-MacFarlane as a personal enemy. To try to resolve the Danzig crisis, in May 1939, Pope
Pius XII sent the Papal Nunico to Germany, Monsignor
Cesare Orsenigo, to meet the
Führer at Berchtesgaden to discuss a possible peaceful resolution to the crisis. General
Gerhard von Schwerin, seeing Mason-MacFarlane's remarks as a way to persuade Hitler not to launch a "premature" war in 1939, met him to ask if he was speaking on behalf of himself or the British government. However, Schwerin offended "Mason-Mac" with his question, which he regarded as questioning his honour as an officer, and the meeting ended badly. In late May 1939, Mason-MacFarlane was recalled from Berlin and promoted to the rank of Brigadier-General of
Royal Artillery at
Aldershot. By this time, he had ceased to be a source of information about Germany and more of an advocate of the particular policies he wanted Britain to follow, as he ventured into grand strategy, stating what policies he favoured as the best way of defeating Germany. The Canadian historian
Wesley Wark wrote: " Mason-Macfarlane represents the extreme case of a military attache who abandoned the uses of ambiguity in favour of single-minded and reductive reporting that made no effort to balance the strengths and weaknesses inherent in a military situation, or the gains and losses implied by a British response...He was influential, as we have seen, in the British decision not to back Czechoslovakia at the height of the Munich Crisis. He was equally influential in the British decision to support Poland and create an Eastern Front on her borders in March 1939. An Eastern Front designed to deter Hitler, based on Czechoslovakia and with the possibility of Russian assistance, had some chance of success. Such a front based on Poland and without Russian participation had none whatsoever". ==Second World War==