- Bellamy: "I have it... at last! In this chest!... The Fragment of Eden!"
- Alonzo: "...A fragment of Eden?"
- Bellamy: "A device with a mind of its own... strong enough to bend wills and shape destinies!"
- Alonzo: "...We could use it!... Become the kings of the seas!"
- Bellamy: "That is what my enemies would do... corrupt its purpose to secure power! Spread a form of slavery that is more insidious than the trafficking of humans... but just as evil!"
- —Samuel Bellamy, explaining the Fragment's powers and desirability, February 1717.[src]
The "Fragment of Eden" was an ancient artifact created by the First Civilization. It held powers similar to that of an Apple of Eden, but was also used to empower one's ship, boosting its speed and firepower.
Samuel Bellamy then took the Whydah for himself to misdirect the Templars into chasing him, while handing the artifact to Alonzo. During Alonzo's efforts to gather supplies for the failing town of Nassau, which was led by Christopher Condent in Edward Thatch and Benjamin Hornigold's absence, he passed the artifact into Levasseur's care, but soon discovered on his return that the pirate had taken the artifact and left, leaving clues behind to guide Alonzo after him.
While on his search to retrieve the Fragment, Alonzo came across the wreck of Olivier's ship, Le Postillon. He believed his friend had been killed and the Fragment to be in the hands of the Templars. However, after destroying a slaver fort in rage, he chased the ship that left and heard word of Levasseur's continued existence from captain Barnes, who specified that Olivier had used the Fragment to secure a new ship after killing its previous crew. In exchange for Barnes' life, Alonzo was handed Levasseur's decryption codex from which he learned that his friend had sailed to Mayaguana in order to escape the Templars.
Alonzo continued his quest across the Caribbean and eventually learned that Levasseur had joined Thatch's crew and was on his way to Charleston to leave the West Indies altogether. After Alonzo catched up and was reunited with his friend, Levasseur told him he had secured the Fragment in Caicos Islands and, keeping their promise to Bellamy to safeguard the object, the two pirates went to the cave where Levasseur had hidden the artifact.
After retrieving the Fragment from the secret location, they were ambushed by Condent's ship, who demanded the pirates to hand over the artifact. Although Condent's ship was much stronger, Alonzo refused and used the power of the Fragment of Eden to boost the weapons and the speed of his vessel, sinking the vessel of the Templar.
Just as Alonzo had defeated Condent, a British war fleet led by the pirate hunter Woodes Rogers appeared on the horizon. Pressed for time, Alonzo decided that he would delay the fleet, while Levasseur was to leave with the Fragment. Levasseur fled aboard a Portuguese galleon and told Alonzo that if something would go wrong, he'd find a way to tell him where he would hide the artifact. Alonzo then sailed out to meet the British fleet, successfully giving his friend time to sail away safely.
In 2014, Abstergo Entertainment analyzed Alonzo Batilla's memories in order to find the location of the Fragment of Eden and the rest of Olivier Levasseur's treasures, but Alonzo's memories proved useless.