His father, August von Mackensen (1849–1945), was eventually, in 1915, promoted to the rank of Field Marshal: Even after 1918, August von Mackensen would remain an unapologetic high-profile monarchist traditionalist[5] who in 1941, despite his advanced age and the difficulties of travelling in war time, made his way to Doorn (near Utrecht) where, dressed in his full military uniform from the imperial years, he attended the funeral of the former German emperor.

[1] During the First World War Mackensen returned to the army, serving between 1914 and 1917 as adjutant to his friend Prince August Wilhelm of Prussia, and ending up with the rank of "Hauptmann" (Captain).

On 10 August 1926 Mackensen married Winifred Christine Helene Baroness of Neurath (1904 - 1985) at the Leinfelder Hof just outside the little town of Vaihingen (near Stuttgart).

Back in 1916, at the height of the First World War, when she was aged just eleven, Winifred had presented a bunch of flowers to the glamorous young hussar Hans Georg von Mackensen, on his return from a mission to Constantinople.

[8] Close family links on various sides to the aristocratic-military elite from the days of empire continued to help Mackensen's career progression in the diplomatic service of the German Republic.

[10] Despite his relative inexperience and youth, in 1929 he was given temporary charge over the German diplomatic mission to Tirana, at what was an exceptionally critical time for the developing relationship between Albania's ambitious new king and the rest of Europe.

[4][11] In July 1931, a couple of months after republican government replaced the Spanish monarchy, Mackensen was transferred again, to be appointed "first diplomat councillor" (Botschaftsrat) at the embassy in Madrid.

[1][4][12] Following months of political deadlock, everything changed in January 1933 when the Hitler government, spotting a power vacuum, filled it: they lost no time in transforming Germany into a one-party dictatorship.

[14][15] As State Secretary Mackensen's political boss was the German Foreign Minister, Konstantin von Neurath, who also happened to be his father-in-law.

However, by 1937, hurt by various social humiliations he suffered as ambassador in London, Ribbentrop had become a raging Anglophobe, which fitted in well with the increasing tendency towards an anti-British foreign policy.

[18] Neurath had been in post since 1932, but on 4 February 1938 he was removed from office and replaced at short notice by Joachim von Ribbentrop, reflecting a determination on the part of Adolf Hitler to take a more "personally hands-on" approach to Germany's foreign policy.

In one of his last acts as State Secretary, Mackensen had to accept the note of protest against the recognition of Manchukuo from Cheng Tien-fong, the Chinese ambassador in Berlin.

[16] Macksensen might no longer be State Secretary, but the Rome embassy was, in the context of the diplomatic developments of the time, an exceptionally important posting.

[22][a] The American historian Gerhard Weinberg wrote that Mackensen was an "unimaginative diplomat" whose rise was due entirely to being an aristocrat with connections to powerful people.

Mackensen reported to Berlin that the Easter Accords did not mark the beginning of better Anglo-Italian relations, saying that Mussolini just wanted the British to stop recognizing Haile Selassie as the rightful emperor of Ethiopia.

[27] On 25 August 1939, Mackensen personally delivered a letter to Mussolini from Hitler, stating that Europe was on the brink of war, saying Germany would invade Poland at any time and expected Italy to honor the Pact of Steel.

[29] On 30 January 1942 the German ambassador to Rome nevertheless received the considerable honour of being appointed an SS Group Leader ("Gruppenführer") on the staff of Reichsführer-SS Heinrich Himmler.

[31] The Anglo-American invasion of Sicily in July 1943 brought forward various crises for Benito Mussolini, including a crisis in his relationship with his dictator-ally in Berlin.

On 25 July 1943, following a (completely unprecedented) overnight vote of no confidence by the Grand Council of Fascism, the king found the courage to dismiss Mussolini and, four days later, had him arrested.

Since the facts on the ground and reactions to them in Rome and Berlin were highly fluid over the next few days, the details of the differing opinions between Adolf Hitler and Hans Georg von Mackensen that the crisis drew out are not entirely clear.

That was the capacity in which he participated at the Group Leaders' congress, held during the first week of October 1943 in the city hall at Posen (the German name for Poznań).