In the May Coup, Alexander I, King of Serbia, and Queen Draga, are assassinated in Belgrade by the Black Hand (Crna Ruka) organization.

The May Coup was a coup d'état in the Kingdom of Serbia which resulted in the assassination of King Alexander I and his consort, Queen Draga, inside the Stari Dvor in Belgrade on the night of 10–11 June [O.S. 28–29 May] 1903. This act resulted in the extinction of the Obrenović dynasty that had ruled Serbia since the middle of the 19th century. A group of Royal Serbian Army officers led by Captain Dragutin Dimitrijević (Apis) organized the assassination. After the May Coup, the throne passed to King Peter I of the Karađorđević dynasty.

Alexander I was King of Serbia from 1889 until his death in 1903, when he and his wife, Draga Mašin, were assassinated by a group of Royal Serbian Army officers, led by Captain Dragutin Dimitrijević.

Draginja "Draga" Obrenović, née Lunjevica (Луњевица) and formerly Mašin (Машин), was Queen of Serbia as the wife of King Aleksandar Obrenović. She was formerly a lady-in-waiting to Aleksandar's mother, Queen Natalija.

Assassination is the willful killing, by a sudden, secret, or planned attack, of a person—especially if prominent or important. It may be prompted by political, ideological, religious, financial, or military motives.

Unification or Death, popularly known as the Black Hand, was a secret military society formed in May 1911 by officers in the Army of the Kingdom of Serbia. It gained a reputation for its alleged involvement in the assassination of Archduke Franz Ferdinand in Sarajevo in 1914 and for the earlier assassination of the Serbian royal couple in 1903, under the aegis of Captain Dragutin Dimitrijević.