The 22-year-old would-be-jihadist wrote to his reclusive father to say he was itching to join the fight. Hamza trained with explosives and embraced the terror network that killed 3,000 Americans in the September 11, 2001 attacks.
But young Hamza was no run-of-the-mill jihadist recruit. He was the favorite son of 9/11 mastermind Osama bin Laden, who was grooming him to take over as Al-Qaeda's leader, according to US intelligence officials.
More than 100 newly declassified documents were provided to AFP by the Central Intelligence Agency, including two letters to Bin Laden from his son and one from Hamza's mother imploring that he follow in his "father's footsteps."
They included Al-Qaeda correspondence noting the eagerness of Hamza, believed to have engaged in terror raids when he was a teen and propaganda videos at a younger age, to return to his father's inner circle.
The documents are part of a trove of thousands seized during the deadly 2011 US Navy SEAL raid on Bin Laden's hideout.
They shed light on inner workings of the terror network and the debate over its future in light of the security noose tightening around bin Laden and the compound in Abbottabad, Pakistan where he met his fate.
Speculation still swirls about where Hamza, dubbed the "crown prince of terror" by a British MP, was on the night his father died, and no proof has emerged that he was at the compound.
He has not appeared publicly or made any public video statements in years, and his whereabouts remain a mystery, senior US intelligence officials said.
But the documents depict a son describing himself as "forged in steel," ready to join his father on a journey to "victory or martyrdom," and a concerted effort by Al-Qaeda to smuggle the young man to his father's hideout.
"What truly makes me sad is the mujahidin legions have marched and I have not joined them," Hamza wrote bin Laden in an eloquent letter in July 2009, when the son was under house arrest in Iran, according to an English translation provided by the CIA.
"I dread spending the rest of my young adulthood behind iron bars," he added.
"My beloved father, I announce to you that I and everyone, God be praised, are following on the same path, the path of jihad."
- Groomed as successor -
It was not possible to independently verify the origin of the documents or the accuracy of the CIA translation.
Officials said the seized documents showed the "enormous toll" counterterrorism operations had on Al-Qaeda, including its inability to replace leaders it had lost.
"Bin Laden at the time of his death had recognized this peril and planned to bring his son Hamza to his Abbottabad compound to groom him as a successor," a senior intelligence analyst told AFP.
Hamza had not seen his fugitive father in eight years, and described the "pain of separation" he felt at age 13 and his hopes of a reunion as a young man of 22.
"You bid us farewell and we left, and it was as if we pulled out our livers and left them there," he wrote.
After Hamza's release from house arrest, top Al-Qaeda lieutenant Atiyah Abd al-Rahman wrote to bin Laden on April 5, 2011, one month before his death, detailing three possible ways to shepherd Hamza to his father.
The "least dangerous option" was sending him through Pakistan's Baluchistan province, which borders Iran, to the teeming port city of Karachi, Abd al-Rahman said, writing under the pseudonym Mahmud.
Meanwhile, Abd al-Rahman arranged for Hamza "to attend a course on explosives," he wrote.
As the plan emerged, Hamza's brother Khalid wrote to say Hamza should use a fake ID and driver's license to safely navigate Baluchistan.
Abd al-Rahman wrote Bin Laden promising to train Hamza in firing various weapons, adding that the young man was "very sweet and good."