August von Mackensen was one of the most capable German generals of the First World War, commanding at the breakthrough battle of Gorlice-Tarnow, one of the most decisive battles of the war, as well as during the invasions of Serbia and Romania. He was born in 1849 in Schmiedeberg in Saxony, the son of an estate manager. In October 1869 he interrupted his university studies to enlist as a one year volunteer in the 2nd Life Guard Hussar Regiment, serving with that unit during the Franco-Prussian War of 1870-71. After the war he returned to complete his studies at Halle, before in 1873 rejoining the regiment.
In 1880 he was appointed to the General Staff, despite not having attended the war college, remaining there until 1894. From 1891-1893 he served as the adjutant to Count Alfred von Schlieffen, the then Chief of the General Staff. From the General Staff he went to the prestigious 1st (Death’s Head) Life Guard Hussar Regiment, as lieutenant-colonel from 1894 and colonel from 1897. He would wear the uniform of this regiment for the rest of his life.
As an officer with such a prestigious cavalry regiment, he frequently came to the attention of the Kaiser, and in 1898 became an adjutant to Wilhelm II, accompanying him on his visit to Palestine. In 1899 he was raised to the nobility. He was also honoured with an à la suite appointment to the newly created Life Guard Hussar Brigade. In 1908 he was appointed to command XVII Army Corps, with the rank of General of Cavalry.
At the outbreak of the First World War, Mackensen’s XVII Corps was allocated to the Eighth Army under General Max von Prittwitz und Gaffron. His first battlefield experience was not encouraging. At Gumbinnen he attacked entrenched Russian positions, without first conducting proper reconnaissance. His men were cut down, and fled. The situation was eventually restored, but Mackensen had suffered 8,000 casualties, and the news of his retreat caused a panic at Eighth Army headquarters. General Prittwitz ordered a retreat to the line of the Vistula, and on 12 August Mackensen’s corps crossed the river.
His corps soon redeemed itself, taking part in the attack on the Russian right at the battle of Tannenberg, which destroyed the Russian Second Army, and then the first battle of the Masurian Lakes, which pushed the Russian First Army out of the heart of East Prussia.
Although these battles removed the threat to East Prussia, Russian armies still threatened the Austro-Hungarian Empire. The Germans decided to launch an invasion of western Poland to relieve the pressure on their ally. Mackensen’s XVII corps was transferred to the Ninth Army in Silesia and took part in the resulting battle of the Vistula River (28 September-30 October 1914). His corps came within twelve miles of Warsaw (first battle of Warsaw, 19-30 October), before a Russian counterattack forced the Germans to retreat.
On 1 November Mackensen was promoted to command the Ninth Army. The threat to Austro-Hungary was now replaced with a direct threat to Germany Silesia. Hindenburg and Ludendorff responded by moving the Ninth Army back from Silesia to a line between Posen and Thorn, from where it would attack the right flank of the Russian armies advancing through Poland. The German attack began on 10 November (second battle of Warsaw). The advancing Russians were caught by surprise, and their Second Army came close to being cut off. However, Grand Duke Nicholas responded quickly, and the Russians were able to escape from the trap. Despite this, the German attack did stop the Russian invasion of Germany, and the Russians pulled back to a new line around Warsaw.
On 16 April 1915 Mackensen was rewarded for his performance during the second battle of Warsaw with command of a new Eleventh Army, made up of four corps moved secretly from the western front. His new chief of staff was Hans von Seeckt, who would remain with him for the rest of the war, and help plan each of his great victories.
Mackensen’s new army had been created to break the deadlock on the eastern front, and on 2-10 May at Gorlice-Tarnow it achieved just that. Mackensen, with the help of the Third and Fourth Austro-Hungarian armies, punched a hole in the Russian front between Gorlice and Tarnow, at the western end of the Carpathian Front. Mackensen was able to exploit this breakthrough, and his army advanced rapidly through Russian Poland. The Russians were forced to pull back throughout the summer of 1915, eventually taking up a position close to the Pripet Marshes. The fortresses of Przemysl and Lemberg were recovered by the Germans. In June, after the capture of Lemberg, Mackensen was promoted to field marshal and on 4 July his command was expanded to form Army Group Mackensen (containing the German 11th and Bug Armies and the Austro-Hungarian Fourth Army).
This great success gave Mackensen a level of prestige in Germany second only to Hindenburg. When General Falkenhayn, Chief of the General Staff was looking for someone to command the armies in the autumn invasion of Serbia, Mackensen was the obvious candidate. On 16 September 1915 he was appointed to command a new Army Group Mackensen, containing the German Ninth Army, Austro-Hungarian Third Army and the Bulgarian First Army.
The second invasion of Serbia (5 October-December 1915) was another triumph for Mackensen. His German and Austrian armies attacked across the rivers Sava and Danube, east and west of Belgrade. The city fell on 9 October. At the same time the Bulgarian First Army invaded Serbia from the east, and their Second Army from the south east. The Serbs were outnumbered, out gunned and surrounded. Their only rail connection to the Allies (at Salonika) was soon cut, and they were forced to retreat across the mountains to the Adriatic coast. The only disappointment for Mackensen was that he was unable to trap and destroy the Serbian army.
His final success was the invasion of Romania at the end of 1916. Encouraged by the success of the Brusilov Offensive and by Allied promises of territorial gains, Romania declared war on Germany and Austro-Hungary in August 1916. Mackensen was given command of a mixed army of Germans, Bulgarians, Austro-Hungarians and Turks, and invaded Romania from the south. Command of this invasion was split. While Mackensen commanded the forces attacking from Bulgaria, the invasion was used as a chance to remove General Falkenhayn from his post of Chief of the General Staff. He was given command of the German Ninth Army, and attacked western Romania across the Transylvanian Alps.
Mackensen’s troops reached Bucharest on 6 December, after defeating a Romanian army three times larger than his own force. They also occupied the Black Sea port of Constanza. The Romanians were forced back into a tiny enclave around Jassy, on the Russian border, where they managed to hold on until the end of the war. Mackensen was appointed to command the German occupying force in Romania. One of his duties was to oppose the Allies at Salonika.
On 10 November, as the Armistice approached, Mackensen began to clear his troops out of Romania, but he remained in Bucharest, where on 16 December he was arrested by the new government and handed over to the French. He wasn’t released until December 1919. The next month he retired from the army.
After the war Mackensen remained a convinced royalist. As the last surviving German field marshal of the First World War he became a potent symbol for the Nazis, appearing in his Death’s Head Hussar’s uniform with Hitler at a number of military events. He retired from public life after the death of the Kaiser in 1941, and survived for long enough to see Germany lose the Second World War, dying in November 1945.
During his career Mackensen was sometimes accused of being a “court general”, having gained his commands because of his connection to the Kaiser rather than through his own ability. His performance on the eastern front in 1915 and 1916 clearly disproves this idea. He was a very able general, capable of exploiting the breakthroughs his attacks created. He was never tested against the British or French on the western front, but he eventually defeated every army he was asked to attack.