King Alexander I of Yugoslavia was shot dead in Marseille on October 9, 1934, within minutes of landing for a state visit. He was riding in an open car with the French foreign minister Louis Barthou when a man ran into the road and fired into the vehicle. He died at the scene. Barthou was hit in the arm and bled to death over the next two hours, which is why the case is still argued about: the round that killed him is thought to have come from a French policeman's revolver during the shooting that followed.
The gunman was Vlado Chernozemski, a Bulgarian who had spent years as a contract killer for the Internal Macedonian Revolutionary Organization and had been trained and armed by the Ustaše, the Croatian separatist movement that Ante Pavelić ran from exile with Italian backing. The gunman died too. He was beaten by the crowd and the police within minutes. A newsreel cameraman had been filming the arrival and kept turning, so the assassination was shown in cinemas across Europe within days, the first ever recorded on film.
Alexander had become a target through what he had done to his own country. The Kingdom of Serbs, Croats and Slovenes was held together by a Serb-dominated centre, and by 1928 the parliament had broken down completely after a deputy drew a revolver and shot four members of the opposition on the floor of the assembly, killing one, which was the crisis Alexander answered with a coup. In January 1929 he abolished the constitution, dismissed parliament, banned parties with national or religious platforms, renamed the state Yugoslavia and ruled through ministers he appointed.
Barthou's death mattered as much as the king's in European terms. He was the foreign minister who had been assembling the alliances against Germany, had just brought the Soviet Union into the League of Nations, and left no successor of the same weight. The League's answer was the first attempt to write counter-terrorism into treaty law, a convention drafted at Geneva in 1937. Yugoslavia took the case to the League. France extradited nobody. Pavelić was tried and sentenced in absentia before going on to rule the Croatian state during the Second World War.