Von Koller spent his military career ascending the ranks through service in various regiments of the Imperial and Royal Hussars. In 1848, as a batman, he fought on the Austro-Hungarian side in the First Italian War of Independence, at the Battle of Sommacompagna, a skirmish by the Salizone, and the Battle of Custoza. In 1849, he distinguished himself in skirmishes at Borgo San Siro and Gambolò. In 1859, during the Second Italian War of Independence, von Koller was awarded the Knight's Cross of the Order of Leopold for his service. In 1866, during the Third war, he was admitted to the Order of the Iron Crown, Second Class, was promoted to the rank of lieutenant field marshal, and received command of the Imperial and Royal 5th (Nicholas I, Emperor of Russia's) Dragoons. In 1868 he became leader of the lieutenancy in Prague. For this service he was promoted to the First Class of the Order of the Iron Crown and was admitted to the Privy Council.
After a period as military commandant of Pressburg, von Koller was appointed Lieutenant Governor and commanding general of Bohemia in 1871. He succeeded in influencing the 1872 elections for the Bohemian Diet in favour of the "constitutional loyalists," so that despite the Slavic (Czech) majority in the Bohemian population, a German-Austrian majority was assured in the Diet. The measures which von Koller took in pursuit of this goal included corruption and outright violence and ultimately exacerbated the national conflict in Bohemia. His actions in this role were rewarded in Vienna,[1] where he was awarded the Great Cross of the Order of Leopold.
In 1873, von Koller was promoted to the rank of general of the cavalry and in 1874 he was appointed Imperial and Royal Minister of War. On his retirement in 1876, he received the Great Cross of the Order of Saint Stephen of Hungary. In addition to these honours, he was a lifelong member of the Austrian House of Lords and was Captain of the 1st Archers' Life-Guard. He also received honorary citizenship of several Bohemian towns.
A newspaper report of 29 May 1890 claimed that, after a long and difficult illness, "there had been a significant improvement" in von Koller's condition,[2] but in the next edition of that paper on 31 May, it was reported that Koller had died at Baden bei Wien.[3] His funeral was attended by Emperor Franz Joseph I.[4]
