Karl Eidenberger was born on the 4th of August 1892 in Vienna. After attending the Realgymnasium he was found to be fit for military service but like 50% of the young men every year he paid a fee which excused him from military duty and entered the Wiener Stadtwerke-Verkehrsbetriebe - the public transportation service of the city of Vienna. When the war started in 1914 he was called up as was normal and inducted into his local army unit the Landwehr infantry regiment "Wien" number 1. As he had successfully graduated from the Realgymnasium he naturally volunteered for the one year volunteer officer candidates' training. On the 1st of November 1915 he was promoted to Kadett in der Reserve with seniority from the 1st of August 1915. In the Autumn of 1915 his battalion of Landwehr infantry regiment number 1 was transferred to enlarge landwehr infantry regiment number 18, so the boys from Vienna now found themselves attached to a Polish regiment. Karl Eidenberger who suffered from a bad case of dysentery in early 1916 received, meanwhile promoted to Fähnrich der Reserve auf Kriegsdauer in March 1916, the appointment as commander of the Jagdkommando (fighting patrol commander) of this enlarged Landwehr regiment. With this unit, mixed from Polish, Ruthenian (Ukrainian) and Viennese men, Fähnrich Eidenberger received the Silver Bravery Medal 2nd class (published June 1916), the Golden Bravery Medal (published March 1917) and the Silver Bravery Medal 1st class (published June 1917) within a few months. It is a fine example of the large difference between the dates when the medals were won, received and the awards finally published due to the slowness of the bureaucracy!
In summer 1916 the Russian Brussilov offensive was held along the river Stochod. The Russians repeatedly attempted to cross the river, building small bridgeheads which were eliminated as soon as possible by the Austrian troops. One of the more geographically useful places was a sandy hill near Zareszcze which was taken and retaken several times within a few weeks but neither side were able to hold this location longer than 24 hours. Landwehr infantry regiment number 18 as a component of Generalmajor von Stöhr's 45th Landwehr Infantry Division was located in this area and commonly referred to it as "Dead Mens' Hill". On the 3rd of August 1916 Fähnrich Eidenberger was ordered to occupy the southern part of the Austrian trenches which pointed at an angle of about 30° and a distance of about 15 metres to the Russian trenches on the top of the hill. With his unit, a cadet, a Feldwebel and about 45 men, he occupied the position there during the night whilst both sides exchanged numerous hand grenades. When the morning of the 4th of August dawned, a heavy fire fight between these trenches commenced. At noon they received the order to assault the hill at 1 o'clock, capture the first trenches and also after some artillery support if possible the main trenches too. The Russians were so surprised at being attacked in broad daylight that Eidenberger's men were able capture the enemy trench after a very short sharp assault. He perceived that the hastily fleeing Russians withdrew in such disorder into the main trench system that he decided not to wait for the artillery and immediately continued the attack. The small but motivated group of Austrians were also able to take the main trenches taking hundreds of prisoners and a huge pile of equipment. Not long after the prisoners were transported to the rear, the Russians, supported by artillery fire, counter-attacked harder than ever. Fähnrich Eidenberger's group was now trapped on the top of the hill and attacked by a force thirty times their size but they were able to hold the "Dead Mens' Hill" until reinforcements could reach them around 8 o'clock in the evening. The Jagdkommando was ordered to go back to the shelters at the ditch along the road behind the hill while the trenches were now occupied by fresh Austrian and German troops. However this order was easier to give than to execute, the whole route back was covered by the fire of Russian guns Finally they reached their shelters at 11 o'clock that night. They had suffered 7 fatalities and nearly everyone of them was wounded.
But there was no rest for them! Just at the moment when Fähnrich Eidenberg gave the order to sleep he saw soldiers running down the hill, some of them without weapons and caps, some of them even without their boots. He stopped some of these panicked runaways and was informed that the Russian had again broken into the trenches on the hill. One can imagine how hard it was to rouse his exhausted men and to tell them to attack the same hill as yesterday again! Fähnrich Eidenberger formed all readily available men into a new assault group and immediately crossed the road where they surprised the first Russian soldiers. The Russians did not expect any counter attack and were nearly running out of ammunition so it was relatively easy to hold them. During the next 4 hours of darkness the Austrians stormed back to the top of the hill supported on the left flank by a Bavarian company. The early morning sun found them back again on the summit of "Dead Mens' Hill" Again they captured many prisoners and much equipment including 6 machine guns. The retreating Russians were now caught by the fire commenced by the Austrian artillery on the other side of the hill. Whilst in the main trenches on the top of the hill a German officer from the German General Berhardi reported to Fähnrich Eidenberger and congratulated him on his victory. He asked him about his personal details and informed him that he had liberated parts of a battalion of German prisoners of war during his night attack. For this action he was honored with the Prussian Kriegerverdienstmedaille (Fighters' Merit Medal) in October 1916 (published 7th November 1917!).
During the following weeks "Dead Mens' Hill" changed hands several more times and finally the hundreds of human cadavers and half buried dead bodies made it impossible to reoccupy the trenches there and the position was abandoned. Fähnrich Eidenberger was transferred back to the Ersatz-Bataillon (Replacement Battalion) in Vienna where he was decorated with the Golden Bravery Medal on the 22nd of November 1916 by Oberst Brunn. On the 1st of November 1916 he was promoted to Leutnant der Reserve with seniority from the 1st August. During 1917 he was appointed as an instructor for assault tactics. In 1918 he suffered for some weeks with typhoid but after his recovery he was transferred back to the field with Landwehr regiment number 1 where he received the commendation of the Kaiser which allowed him to wear the Bronze Military Merit Medal (Signum Laudis) with war decoration and swords on the 9th of October 1918. Finally he was promoted to Oberleutnant der Reserve on the 1st of November 1918.
Very little is known about his postwar life. Karl Eidenberger went back to his civil profession with the Viennese Tramways, married in 1920 and had 2 children born in 1922 and 1929. He died on the 22nd of August 1976 in Vienna.