[8] Following Austria-Hungary's withdrawal from Pljevlja on 20 October 1908,[6] Rhemen was appointed commander of the 34th Infantry Division in Temeschwar (modern-day Timișoara, Romania) on 14 March 1909.

[18] On 12 August 1914, General Oskar Potiorek ordered the invasion of Serbia, with Adolf von Rhemen's XIII Corps forming a key part of the offensive.

Positioned along the lower Drina river in Bosnia, the Fifth Army, under Liborius Ritter von Frank, was tasked with encircling the Serbian centre at Valjevo.

On 6 September 1914, under Allied pressure, Serbian General Petar Bojović launched a counteroffensive into Austria-Hungary, capturing Semlin (Zemun) in Syrmia.

[36] On 15 November, XIII Corps played a key role in the capture of Valjevo,[37] with Rhemen's units continuing their pursuit of Serbian forces into the Kolubara region.

[38] The occupation was short-lived, as a massive Serbian counteroffensive began on 3 December, targeting Rhemen's XIII Corps along the Kolubara River.

[42] The Serbian campaign had been a disaster for Austria-Hungary, as 450,000 Austro-Hungarian troops failed to defeat Serbia's numerically inferior forces.

[43] Rhemen's XIII Corps suffered heavily, contributing to the 273,804 Austro-Hungarian casualties, including 28,000 dead, 122,000 wounded, and 40,000 missing.

[47] Reports indicate that Austro-Hungarian troops engaged in executions, mass reprisals, and destruction of villages in the Mačva region, Jadar valley, and areas near Loznica and Lešnica.

[49][50] Swiss criminologist R. A. Reiss, who investigated the atrocities, concluded that thousands of Serbian civilians were massacred with extreme brutality.

[51] On 13 August 1914, Potiorek issued punitive orders instructing all units, including XIII Corps, to seize hostages, conduct reprisal executions, and burn villages in response to Komitadji partisan activity.

[52] Some of these actions were carried out by the 42nd Home Guard Division near Zvornik, as well as other units in Krupanj and Zavlaka, where entire groups of civilians were executed after being tied together.

[49][48] Sources suggest that Rhemen justified these atrocities by describing the Serbs as "a culturally backward people", arguing that adhering to the laws of war was impractical in such conditions.

[17][53] Following the failed Serbian campaign, Adolf von Rhemen's XIII Corps was redeployed to the Carpathian Front in mid-January 1915.

[55] Now under Seventh Army command, XIII Corps was headquartered in Kolomyya, Ukraine, under General Karl von Pflanzer-Baltin.

[58] In July 1916, following the corps' heavy losses, Rhemen was dismissed from command and replaced by Lieutenant Field Marshal Maximilian Csicserics von Bacsány.

[8] Additionally, Rhemen's fluency in Serbo-Croatian, acquired through his service in the Sanjak of Novi Pazar and Croatia, made him a suitable candidate for leadership roles in the region.

[65] Rhemen's appointment signaled a stricter regime during the Austro-Hungarian occupation of Serbia, promising to impose "order and justice".

In a letter to the emperor, he stated: "I ask His Majesty to note that despite General Rhemen's excellent personal qualities, I also harbor reservations due to his relationships in Croatia.

I respectfully submit that, in the interest of preventing further disruptions, it would be highly desirable for Hungarians to be appointed to both positions, individuals of non-Slavic origin with no ties to South Slavic communities.

[67] Within two months, 16,000 Serbs were sent to internment camps; by the end of the year, the number reached 70,000, causing a severe labor shortage in the MGG/S.

[69] In early 1917, during the Toplica uprising, a large-scale rebellion against the occupation, Rhemen ordered the "ruthless extermination" of Chetnik bands.

[73] On 28 October 1918, as the Serbian army and Allied forces advanced on occupied Serbia, Rhemen departed the region with his staff and Baron Kuhn, the Foreign Ministry's representative.[74].