Gavrilo Princip was trained by Black Hand. My understanding is that Black Hand was a paramilitary organization in service to the royal family. Their aim was to create a Serbian nation outside of the Austro-Hungarian empire. They killed the Duke to start a war in the expectation that they could forge a new nation. Since Yugoslavia formed after WWI, you have to say that they were successful. I am not a historian but my wife's grandfather was a member of Black Hand. Her family was mercilessly persecuted by communists after they took over in 1947, so I think Black Hand was a nationalist organization, not communist.

Edit: to add to this, my grandparents were living in Yugoslavia during the WWI and post WWI period. Despite not being Serbian, they were treated normally by the Yugoslavia government prior to World War Ii. Thankfully they left because when the communists took over, everyone in their village was purged.

Gavrilo Princip was trained by Black Hand. My understanding is that Black Hand was a paramilitary organization in service to the royal family. Their aim was to create a Serbian nation outside of the Austro-Hungarian empire. They killed the Duke to start a war in the expectation that they could forge a new nation. Since Yugoslavia formed after WWI, you have to say that they were successful. I am not a historian but my wife's grandfather was a member of Black Hand. Her family was mercilessly persecuted by communists after they took over in 1947, so I think Black Hand was a nationalist organization, not communist.