Background
He was born to father Milan and mother Joka in Podnovlje municipality Doboj in present-day Bosnia and Herzegovina. Nikola lived with his father at first so he attended school in places where his father served with the Serbian army.
He was born to father Milan and mother Joka in Podnovlje municipality Doboj in present-day Bosnia and Herzegovina. Nikola lived with his father at first so he attended school in places where his father served with the Serbian army.
He eventually finished six grades of gymnasium before becoming a student of geodesy in Belgrade.
He had a sister named Angelina, born 1912. Nikola"s father separated from Joka after World War I and proceeded to get married three times. During his studies, he met Borka (a year younger than him) who was born in Rajkovići near Valjevo in present-day Serbia into a family of old supporters of the People"s Radical Party and Nikola Pašić.
Their first service was in Belgrade.
They then moved to Aranđelovac and finally back to Valjevo (where there are Kalabićs today). Nikola Kalabić (until the start of ) worked in Land-registry management in Valjevo.
During, Nikola Kalabić was commander of Mihailovic"s elite formation named Mountain Guard Corps (Serbian Cyrillic: Корпус горске гарде). On 26 November 1943, he together with Colonel Simic, General Inspector of Chetnik Troops, concluded a formal collaboration agreement (German: Waffenruhe-Verträge) with the representative of the German Military Commander in Southeast Europe, General der Infanterie (Lieutenant General) Hans Felber.
Near the very end of the war, Kalabić like many other Chetniks, tried to hide in rural areas of the country, awaiting an attempt to overthrow the new government.
There, OZNA agents infiltrated the support network of Kalabić and arrested him in a covert operation on 5 December 1945. After a few days, Kalabić agreed to collaborate with the OZNA in their efforts of locating and arresting Draža Mihailović, in return for immunity from prosecution.
The OZNA had a plan to capture former members of the Chetnik movement and other military organizations outside of Yugoslavia. This claim however has been brought into question by family members of Kalabić claiming that he did not surrender Mihailović.