But they rejected him for being, hmm, "too scrawny."
So he went and bombed the Archduke to show that he could *TOO* be a decent terrorist.
As Leslie Winkel from The Big Bang Theory (cwidt?) would put it,
"Dumbass."
“...So he went and bombed the Archduke...” [grey_whiskers, post 5]
Gavrilo Princip did not bomb anyone.
He shot Franz Ferdinand and wife Sophie with an FN M1910 auto pistol, chambering in 7.65mm Browning (US 32 ACP). Two shots, two deaths. Auto pistols were so new and unknown at the time, that many newspaper illustrators of the day sketched in a revolver when drawing their depictions of the event.
Franz Ferdinand was wearing an early type of soft body armor, invented by an American clergyman from Chicago. But Princip shot him in the neck, which wasn’t protected.
One of the automobiles in Franz Ferdinand’s procession made a wrong turn, placing the party in Princip’s sights by mere chance - after he’d given up hope of getting near his target and was walking back to the conspirators’ hideout. He was stopping to buy a sandwich when the vehicles came into range.
A long list of bad luck and blunders, presaging the blunderful mess of the war which followed.