Arthur Arz von Straußenburg

At the outbreak of war in the Summer of 1914, Arz von Straussenburg requested a transfer to a field assignment and was again given command of the 15th infantry division,[4] which participated in the closing stages of Komarów. Almost immediately thereafter, on 7 September, Arz was given command of the 6th corps, taking over from Boroević, who had been appointed to command the Third Army. In charge of the 6th Corps, he performed outstandingly and with great energy at Limanowa-Lapanów, where his unit formed part of the 4th Army. At Gorlice-Tarnów he was again to play an outstanding role and was in command again at Grodek-Magierow and Brest-litowsk during the summer of 1915. In September 1915, he was promoted to the rank of General der Infanterie, and having fought alongside Mackensen's 11th army he gained the respect of the Germans in his abilities as a commander.

With the threatened entry of Romania into the war on the Allied side, Arz was reassigned from the 6th Corps and appointed to command the newly reorganised 1st Army on 16 August 1916. Arriving at Kolozsvár (today Cluj-Napoca, Romania), where forces were being marshalled to repel an expected Romanian advance into Transylvania, he stated "I am an Army Commander without an Army". Indeed, on the Romanian declaration of war on 27 August, the 1st 'Army' comprised a mere 10,000 men (half a division). A slow Romanian advance combined with hysterical outcry from Budapest led to the 1st Army being considerably and rapidly strengthened to drive back the challenge from the south.

Disposition of Romanian forces in Austria-Hungary, August 1916

Romanian forces crossed the frontier on 28 August 1916 with six separate forces pushing through the six Carpathian passes to converge on Brassó (today Braşov, Romania). By 4 September they had succeeded in pushing nearly as far as Sepsiszentgyörgy in the Székely territories. In order to fend off these six separate invasions, Arz, now fighting on his home turf, ordered the 71st Infantry Division and 141st and 142nd Brigades to the sector. Simultaneously, the Romanian North Army sought to advance along the entire Moldavian front in the Eastern Carpathians, although in fact this amounted to an advance in the northern sector, where the Russian 9th Army was best placed to aid the advance. To counter this strike, Arz deployed the 16th, 19th and elements of the 61st divisions.

In cooperation with the German 9th Army, the Romanian invasion was repelled and its forces were thrown back across the border within eight weeks, leading to Arz receiving the respect and appreciation of the new Austro-Hungarian emperor, Karl I. Other commanders also hailed his achievements during the campaign, with Conrad writing that he had "proved to be an energetic resolute leader in the most difficult situations..." and Boroević stating that Arz was an "Honourable, noble character....outstanding general."

Arz was to remain in charge of the 1st Army until February 1917, after major operations in Romania ended, with help from Falkenhayn's 9th German Army and from the German Army of the Danube under Mackensen.

Arz von Straußenburg's coat of arms, granted in 1918

Karl I of Austria succeeded Franz Joseph as Emperor on 21 November 1916, bringing with him a wave of change across the upper echelons of the government and military command. One casualty of these changes was Conrad, with Karl reported as "not wanting a genius to command his armies",[5] but following on from the experience of the supremely gifted but often unsuccessful Conrad, rather someone who was just capable. Arz was acquainted with the emperor; not only was he a capable commander of troops, but he also possessed a conciliatory manner which did not make the Emperor feel he was being patronised during discussions on military matters, as was the case with other commanders. Unlike Conrad, Arz was not overtly political, was wholly committed to the Central Powers, and had full faith in the Emperor.

Once appointed in March 1917, Arz made every effort to comply with the Emperor's wishes, but unlike his predecessor he acted as a personal advisor to the Emperor on army matters, rather than as a driver of his own strategy, which had been Conrad's hallmark. His tenure at the head of the army saw increasing German control over Austro-Hungarian forces and reduced independence of action, but also a number of notable victories in the spring and summer of 1917, including the clearing of Galicia and the Bukovina, as well as the breakthrough at Flitsch Tolmein and the great victory at Caporetto later in the year.

Arz (right) with Ludendorff (left) at Army Headquarters in Baden bei Wien, 1917

Promoted to the rank of Generaloberst on 26 February 1918, and also raised to the nobility early the same year, Arz was ultimately responsible for planning the invasion of Italy which was to take place during the summer of 1918, with Russia now knocked out of the war and a good number of experienced forces at his disposal. While planning was underway, both Conrad and Boroević demanded to lead the offensive, and neither Arz nor the AOK was able to make a decisive decision. Instead a compromise suggested by the Emperor was adopted, with their forces divided and sent to attack Italian positions on the front from two different directions. This resulted in the utter failure of the offensive at the Piave River in June 1918.

Arz took full responsibility for the failure of the massive invasion of Italy and tendered his resignation, but the Emperor refused to accept it, even after Generaloberst Schönburg-Hartenstein had said to the Emperor's face that the army had lost all confidence in Arz. By late October 1918, Arz could see that ultimate defeat for the Imperial forces was inevitable. He had drawn up plans for an orderly troop withdrawal in the event of an armistice, so as to prevent unnecessary further bloodshed. An armistice with Italy was concluded on 3 November 1918 and was to come into effect 36 hours later, during which time thousands of Imperial troops were captured while believing themselves to be at peace, due to poor communication from Army High Command.

During the night of 2–3 November 1918, the Emperor relinquished command of the armed forces. In a handwritten note which can still be found in the Vienna war archives, he wrote:

Dear Generaloberst Baron Arz, I appoint you to be my supreme commander. Karl

Not wanting responsibility for handling the armistice, Arz declined the appointment, and Kövess took up appointment as commander-in-chief instead. Arz however undertook the position de facto until Field Marshal Kövess could take up his office.