You're probably tired of crackpot theories and ideas.
So here's a little fan-fiction of what happened 22 years ago. It's based on a couple of my ideas about Raftel and such.
50 or so years ago in North Blue, a boy was born during a great struggle against two opposing forces. The boy was one of the last children of a kingdom involved in a civil war. His parents were taken from him when he was very young. The world government wanted to end this as soon as possible, so they sent a Buster Call to the island. The boy had heard of this and was ready to die, when a goat wandered along. The boy, being desperate, asked the goat to swallow him and hide him.
When the dust cleared from the BC, the goat had died, but the boy was still alive. He cut open the goat's stomach and looked outside, only to find that everyone had died.
The marines saw the boy and took him aboard their ship. He asked them what had happened, and the marines lied and said that the opposing force had resisted the World Government and an accident caused everyone to die. The boy was devastated, and asked to join the marines so atrocities like this could never happen again. The boy discarded his old name and named himself Sengoku, or Civil War. As a product of such, he would be forever bound to it. He also adopted a pet goat in thanks to the goat that had saved his life.
Several years later, the man had a son, Kuzan. Kuzan was a very spoiled fellow, and as a result was very lazy. However, like his father, he was very smart and resourceful. He too joined the marines and became an admirable soldier.
Then game Gol D. Roger and his crew. Sengoku had learned of Roger and his piracy through many various sources, including one from Skypeia, a top secret island in the sky that few knew about and many thought lost. Roger was a hero to many because he gave hope to the people and wanted to reveal the Lost Kingdom to the world. Sengoku knew the Gorosei would not allow this.
the Gorosei would not. They sent the head of the Marines to the waters around Raftel, which contained the legendary Seaking Hydra. They also gave him the Tore Tore no Mi, or Trainer (without the -na) fruit, which gave him power over beasts. He subdued the Hydra and ordered it to attack the Oro Jackson as it approached. Roger's crew easily decimated the Hydra and defeated the leader of the Marines.
The Gorosei were furious, but undaunted. They could now allow Roger to reach Raftel for any reason. He could not see ground-zero. Since they were too old to fight anymore, they gave Vice-Admiral Sengoku and then de-facto Marine leader four devil fruits and told him to find the most powerful marines in the world to fight against Roger and his crew. Sengoku agreed and took the devil fruits, eating one himself.
From South Blue he picked his son, Kuzan, who had been stationed there as a Commodore. From East Blue he choose a famous marine, and from West Blue he choose Sukazuki, then a Captain. He gave them all temporary vice-admiral status and one of the devil fruits. Based on a story he had heard as a boy, he also named them after the animals of legend, Ao Kiji, Aka Inu, and Kiro Sauru.
The four of them went to Raftel, where Roger had already made a base. There they found the head of the marines, still being held prisoner. They freed him and then began fighting the Pirates of Gold.
In the end, it was a fierce battle, but because of the power of their devil fruits combined, The crewmates were defeated one by one, until Roger was the only one standing. Roger agreed to surrender on condition his crewmates were not harmed. Whitebeard threw himself in front of the captain and refused, stating that as King of the Pirates, they could not allow him to surrender without giving their lives. Roger responded by slashing Whitebeard across the chest and knocking him out.
Sengoku was appalled at Roger's actions, and demanded a fair fight against the Captain. Roger refused, saying that everyone had achieved their dreams and it was pointless to continue fighting. Roger's only wish was that their crew be allowed to continue living their dreams and in return would not reveal what they saw on Raftel, plus Roger would give himself up to the Marines.
Dragon refused to accept this, and declared war on the World Government. Using his powers, Dragon scattered the crew of the Oro Jackson across the world and stated that the Gold Pirates would not keep their silence forever. There were those other than Roger that carried the Will of the Dead. He then vanished in a flurry of winds, leaving Roger alone on the island.
Before they escorted Roger away, he took out a piece a paper and wrote something on it, then left it sitting on a rock. He then told the marines that each of his crew had a piece of paper with something on it. When combined, it would show the way to the truth. Of course, no one payed him any mind.
Roger requested to be executed in Loguetown, and the Gorosei granted his last request. Sengoku was given the second highest position in the Marines as thanks for his efforts, and his companions, including his son, were promoted to vice-admiral as well. In order to ensure that no one, including the former Gold Pirates, would get to Raftel again, the Marines captured several seakings of the largest variety and arrayed them around the island.