The three Black Hand trainees secretly made their way back to Sarajevo roughly a month before Franz Ferdinand. A fourth man, Danilo Ilic, had joined the group and on his own initiative, recruited three others. Vaso Cubrilovic and Cvijetko Popovic were 17-year-old high school students. Muhamed Mehmedbasic, a Bosnian Muslim, was added to give the group a less pan-Serb appearance. Four Serbian army pistols and six bombs were supplied from Serbian army arsenals.
Franz Ferdinand accepted the invitation of Bosnia's governor, General Oskar Potoirek, to inspect the army manoeuvres being held outside Sarajevo. The Archduke's role as Inspector General of the Army made the visit logical. It had also been four years since a prominent Hapsburg had made a goodwill visit to Bosnia. The visit would also roughly coincide with his 14th wedding anniversary. While his wife Sophie, not being of royal blood, was not permitted to ride in the same car as her royal husband back in Vienna, such taboos did not apply to provincial cities like Sarajevo. During the visit, Sophie would be able to ride beside her husband - a thoughtful anniversary gift.
Security during the visit was not tight. Franz Ferdinand was a brave man and disliked the presence of secret service men. Nor did he like the idea of a cordon soldiers between the crowd and himself. For the most part, the Bosnians welcomed Franz Ferdinand warmly. Sarajevo was not seen as hostile territory. Arrangements were not based on the assumption that the streets were lined with assassins. As it was, only Sarajevo's hundred and twenty policemen were at work.
At around 10:00 am, the archducal party left Philipovic army camp, where Franz Ferdinand had performed a brief review of the troops. The motorcade, consisting of six automobiles was headed for City Hall for a reception hosted by Sarajevo's mayor. The chosen route was the wide avenue called Appel Quay, which followed the north bank of the River Miljacka. The morning was sunny and warm. Many of the houses and buildings lining the route were decorated with flags and flowers. Crowds lined the Appel Quay to cheer the imperial couple. Amid the festive crowd mingled seven young assassins. They took up their assigned positions, all but one along the riverside of the Appel Quay.
The motorcade approached, and the crowds began to cheer. As Franz Ferdinand's car passed Mehmedbasic, he did nothing. The next man in line, Cabrinovic, had more resolve. He took the bomb from his coat pocket, struck the bomb's percussion cap against a lamppost, took aim and threw the bomb directly at Franz Ferdinand. In the short time it took the bomb to sail through the air, many small events took place. The car's owner, Count Harrach, hearing the bomb being struck against the lamppost, thought they had suffered a flat tire. The driver, who must have seen the black object flying, stepped on the accelerator. As a result, the bomb did not land where intended. Franz Ferdinand, also catching a glimpse of the hurtling package, raised his arm to deflect it away from Sophie. She sat to his right, and so was between Franz Ferdinand and Cabrinovic.
The bomb glanced off Franz Ferdinand's arm, bounced off the folded car top and into the street behind them. The explosion injured about a dozen spectators. The third car was hit with fragments and stalled. Merizzi received a bad cut to the back of the head. Others in the party received minor cuts. The first and second cars continued on for a few moments then stopped while everyone assessed who was injured and who was not.
Cabrinovic swallowed his cyanide and jumped into the river. The trouble was, the poison was old, it only made him vomit, and the river was only a few inches deep. He was quickly seized by the crowd and arrested. The motorcade continued on to City Hall, passing the other assassins. Either because they thought Cabrinovic had succeeded or from lack of resolve, they failed to act.
Discussions were held as to whether to change the rest of Franz Ferdinand's schedule. The Archduke did not wish to cancel his visit to the museum and lunch at the Governor's residence, but wished to alter his plans to include a visit to Merizzi in the hospital.
The same motorcade set out along the Appel Quay, but neither the Mayor's driver, nor Franz Ferdinand's driver had been informed of the change in schedule. This would have been Merizzi's job. The young assassins had counted on succeeding on the first attempt. With no assurance that Franz Ferdinand would follow his original itinerary, the remaining assassins took up various other positions along the Appel Quay. Gavrilo Princip crossed the Appel Quay and strolled down Franz Joseph Street. He stepped into Moritz Schiller's food store to get a sandwich.
The Mayor's car, followed by Franz Ferdinand's car turned off the Appel Quay and onto Franz Joseph Street, as originally planned, to travel to the museum. Franz Ferdinand's car stopped directly in front of Schiller's store - five feet away from Princip.
Princip was quick to recognize what had happened. He pulled the pistol from his pocket, took a step towards the car and fired twice. General Potoirek happened to look directly at Princip as he fired. He thought the gun's report unusually soft. Both Franz Ferdinand and Sophie were still sitting upright. Potoirek thought the shots had missed, but given the assault, ordered the driver to drive directly to the Governor's residence.
Princip then turned the gun on himself, but was mobbed by the crowd. Police had to rescue Princip from the crowd before they could arrest him. Princip had swallowed his poison, but it was from the same batch as Cabrinovic's. He was violently ill, but did not die.
As the car sped across the Lateiner Bridge, a stream of blood shot from Franz Ferdinand's mouth. He had been shot in the neck. Sophie sank from her seat. Potoirek and Harrach thought she had fainted and were trying to help her up. Franz Ferdinand, knowing his wife better, suspected the truth. Sophie had been shot in the abdomen and was bleeding internally. The cars rushed to the Governor's residence. Sophie may have died before they arrived. Franz Ferdinand died shortly afterward.
The murders of Franz Ferdinand and Sophie brought Austro-Serbian tensions to a head. Serbia had been fomenting trouble for Austria for many years. For many in Vienna, the double murders provided the 'last straw' for a get-tough showdown. The trail back to the Black Hand would not be unravelled for years to come. Vienna felt she could not wait for conclusive proof and acted based on the mass of circumstantial evidence. As Vienna took a hard line against Serbia, the other powers in Europe took sides. The wheels of war gained speed. The stakes far outgrew the squabble between Austria and Serbia. The Crisis of July turned into world war; just over thirty days after Franz Ferdinand and his wife Sophie were shot.