One Piece covers the Rocky Harbor Incident after the time skip, involving some of the most important characters in the series.
Koby is recognized as a Marine Hero, like his teacher Garp. However, the manga never goes deeper into what actually happened at that event. Luckily for One Piece fans, Oda answered questions regarding the event in Weekly Shonen Jump's latest Q&A session.
This SBS included 10 important questions related to the One Piece series, and the ninth question explained the truth behind the Rocky Harbor Incident.
The question contains: “Please tell us about the Rocky Harbor Incident that led to Koby being hailed as a Naval Hero?”
Oda replied: “Because explaining like that would take too long and I don't think this will be described in the main plot by 'This is a summary of the Rocky Harbor Incident'. It is said that Pirate Island holds a important Poneglyph, Law hijacked a giant passenger ship called Rocky Harbor and infiltrated the island.
The ship happened to be carrying the king and important nobles of a certain country. However, the ship that Law wants to board is actually a smuggling ship, flying the flag of the same country and related to Pirate Island, leading to big trouble.
Law came into conflict with the pirates, and soon after, Koby and Blackbeard came to the island for their own reasons, leading to the three of them joining forces. As a result of this incident, Blackbeard became the crab of Pirate Island, Law was recognized as one of the Shichibukai and Koby was hailed as a hero.”
So we know, it turns out the Rocky Harbor Incident was an unusual alliance between Law, Koby, and Blackbeard. However, this alliance was only temporary as they continued to be enemies afterward. During the Egghead Incident arc, Blackbeard destroyed Law's crew and the pirate barely escaped death.
Not only that, he also captured Koby and imprisoned him on Hachinosu Island until Garp and the SWORD members came to rescue him.
