Black Han (Serbian: Црна рука / Crna Ruka), officially Unification or Death (Serbian: Уједињење или смрт / Ujedinjenje ili smrt), was a secret society founded in Serbia in May 1911, as part of the Pan-Slavism nationalist movement, with the intention of uniting all of the territories containing South Slav populations (Serbs, Croats, Macedonians, Slovenes, etc) annexed by Austria-Hungary. This society's possible connections to the June 28, 1914 assassination in Sarajevo of Franz Ferdinand, Archduke of Austria is considered to have been the main catalyst to the start of World War I.