Ennobled as an Austrian baron in March 1858, Gablenz served in the Second Italian War of Independence, where he fought at Magenta and Solferino.

Appointed a Privy Councilor in November 1864, he became the commanding general of the V Corps and was named governor of the Duchy of Holstein, a position he held until the outbreak of the Austro-Prussian War.

At the start of the Austro-Prussian War, which mostly took place in Eastern Bohemia (Czech Republic), Gablenz was considered to be one Austria's foremost generals.

Following the stock market crash of 1873 Gablenz was plagued by debt and fearing the loss of Emperor Franz Joseph's confidence he committed suicide in Zürich on 28 January 1874.

He was first buried at the Zurich municipal cemetery, but in 1905 his remains were transferred into the newly completed crypt of the warrior monument built in 1868 to commemorate the Battle of Trautenau.