Most historians agree that Princip was a member of Young Bosnia; that the group got its weapons from the Black Hand (Црна рука/Crna ruka); and that the latter group was at least somewhat responsible for coordination, training, and/or supplying weapons for the forthcoming assassination attempt on Franz Ferdinand. However, Princip had minimal contact with the group, and did not associate with them. The Young Bosnia movement was a group made up of Serbs, Croats, and Bosnian Muslims, committed to the independence of the South Slavic peoples from Austria-Hungary. In February 1912, Princip took part in protest demonstrations against the Sarajevo authorities for which he was expelled from school. Following his expulsion, he moved to Belgrade. In Belgrade, he sought to gain admission to the First Belgrade Gymnasium but failed the entrance exam.
In 1912, Serbia was abuzz with mobilization for the First Balkan War. Princip planned to join the komite, irregular Serbian guerrilla forces under Serbian Major Vojislav Tankosić which had fought in Macedonia against Ottoman units. Tankosić was a member of the central committee of the secret society Unification or Death (Ujedinjenje ili Smrt). Princip, however, was rejected by the komite in Belgrade because of his small physical stature. He then went to Prokuplje in Southern Serbia where he sought a personal interview with Tankosić. Tankosić, however, rejected Princip due to being "too small and too weak." Dedijer argued that this rejection was "one of the primary personal motives which pushed him to do something exceptionally brave in order to prove to others that he was their equal."
Just before 10 o'clock on Sunday, the royal couple arrived in Sarajevo by train. In the front car was Fehim Čurčić, the Mayor of Sarajevo and Dr. Gerde, the city's Commissioner of Police. Franz Ferdinand and Sophie were in the second car with Oskar Potiorek and Count von Harrach. The car's top was rolled back in order to allow the crowds a good view of its occupants.
The seven members of the group lined the route. They were spaced out along the Appel Quay, each one with instructions to try to kill Franz Ferdinand when the royal car reached his position. The first conspirator on the route to see the royal car was Muhamed Mehmedbašić. Standing by the Austro-Hungarian Bank, Mehmedbašić lost his nerve and allowed the car pass without taking action. Mehmedbašić later said that a policeman was standing behind him and feared he would be arrested before he had a chance to throw his bomb.
At 10:15 A.M., when the six car procession passed the central police station, nineteen-year-old student Nedeljko Čabrinović hurled a hand grenade at the archduke's car. The driver accelerated when he saw the object flying towards him. Then he remembered that it had a 10 second delay and the bomb exploded 10 seconds after, under the wheel of the next car. Two of the occupants, Eric von Merizzi and Count Boos-Waldeck were seriously wounded. About a dozen spectators were also hit by bomb splinters.
After Čabrinović's bomb missed the Archduke's car, five other conspirators, including Princip, lost an opportunity to attack because of the heavy crowds and the high speed of the Archduke's car. To avoid capture, Čabrinović swallowed a cyanide pill and jumped into the River Miljacka to make sure he died. The cyanide pill was very old and made him vomit and the River Miljacka was only 4 inches deep. A few seconds later he was hauled out and detained by police.
Franz Ferdinand later decided to go to the hospital and visit the victims of Čabrinović's failed bombing attempt. In order to avoid the city centre, General Oskar Potiorek decided that the royal car should travel straight along the Appel Quay to the Sarajevo Hospital. However, Potiorek forgot to inform the driver, Franz Urban, about this decision. On the way to the hospital, Urban took a right turn into Gebet Street.
Princip had gone into Moritz Schiller's cafe for a sandwich, having apparently given up, when he spotted Franz Ferdinand's car as it drove past, having taken the wrong turn. After realizing the mistake, the driver put his foot on the brake, and began to back up. In doing so the engine of the car stalled and the gears locked, giving Princip his shot. Princip stepped forward, drew his pistol, and at a distance of about five feet, fired twice into the car. Franz Ferdinand was hit in the neck and Sophie in the abdomen, and they both died before 11am.
Princip tried to kill himself first by ingesting cyanide, and then with the use of his pistol. But he vomited the past-date poison (as did Čabrinović, leading the police to believe the group had been deceived and bought a much weaker poison). The pistol was wrestled from his hand before he had a chance to fire another shot.
Princip was too young to receive the death penalty, being twenty-seven days short of his twentieth birthday at the time of the assassination. Instead, he received the maximum sentence of twenty years in prison. He was held in harsh conditions which were worsened by the war. He died of tuberculosis on April 28 1918 at Theresienstadt (a place which later became infamous as a Nazi concentration camp). At the time of his death, Princip weighed around 40 kilograms (88 lbs), weakened by malnutrition, blood loss and disease.
Gavrilo Princip is a person whose significance and reputation are viewed very differently around the world. He is mostly seen as the man who started World War I, indirectly responsible for the decline of Europe and the death of millions. However, Gavrilo Princip had no way of knowing his actions would spark the Great War; his ambition was the independence of the Yugoslav peoples in Austro-Hungary, in which case he may be viewed as a hero who gave his life for the freedom of the many peoples under Austrian and Hungarian rule (and in a way actually succeeded in this, as the formation of Yugoslavia was a consequence of World War I). These two conflicting reputations have remained throughout the world from the very moment the bullets were fired.
Prior to the 1990s the site on the pavement on which Princip stood to fire the fatal shots was marked by embossed footprints. These were removed as a consequence of the 1992-5 war in Bosnia and the perception of Princip as having been a Serb nationalist. Later a simple wooden memorial was placed near the site of the assassination with the words in Bosnian,Serbian and English "May Peace Prevail on Earth".