Danilo Ilić was born in Bosnia and Herzegovina in 1891 and died in 1915. He attended the State Teachers' College in Sarajevo and for a while taught at a school in Bosnia. In 1913 Ilic moved to Belgrade where he became a journalist and a member of the Black Hand secret society.
Ilic returned to Sarajevo in 1914 where he worked as editor of a local Serb newspaper. He began recruiting young men into the Black Hand group and that summer agreed to help Gavrilo Princip, Nedeljko Čabrinović, and Trifko Grabež to assassinate Archduke Franz Ferdinand.
On Sunday, 28 June, 1914, Franz Ferdinand and Sophie von Chotkow were assassinated by Gavrilo Princip. Princip and Nedeljko Čabrinović were captured and interrogated by the police. They held out but another member of the gang, who was picked up on a routine check, eventually broke down under pressure and named his fellow conspirators. Muhamed Mehmedbašić managed to escape to Serbia but Veljko Čubrilović, Vaso Čubrilović, Cvjetko Popović and Miško Jovanović as well as Danilo Ilić were arrested and charged with treason and murder.
Eight of the men charged with treason and the murder of Archduke Franz Ferdinand were found guilty. Under Austro-Hungarian law, capital punishment could not be imposed on someone who was under the age of twenty when they had committed the crime. Nedjelko Čabrinović, Gavrilo Princip and Trifko Grabež therefore received the maximum penalty of twenty years, whereas Vaso Cubrilovic got 16 years and Cvijetko Popovic 13 years. Illić, Veljko Čubrilovic and Miško Jovanović, who helped the assassins kill the royal couple, were executed on 3 February, 1915.