It was after the Dark Heart death, when the Darkness was pushed beyond the Reef and when the Queen of the Awoken finally acknowledged the rest of us on Earth. She had moved her entire army to Earth, to ultimately and effectively defend the only planet any of us called home.
This was when the event known as the Departure occurred.
What many of us didn't know was how vast the Queens army was. We knew how powerful she was but didn't truly understand it until she arrived on Earth. She took refuge on the cold plains of Alaska and the Arctic, still keeping to her ways of isolation is best. This was fair in return for her overpowered protection.
Well it was shorty after that we seen changes in our way of life. It started with the Guardians Ghost companions acting odd, often refusing to obey or inform of dangers. They would often glow or flash red, then resulting in smart replies or not replying at all. This was put down to the fact that the Guardians have been using the Ghosts for decades, if not centuries. All of them made from the Traveller itself. Eventually these rampant Ghosts, indeed, all the Ghosts, died. They ceased to appear for their Guardians and seemed to vanish altogether. And that was just the beginning.
The next thing to happen was the declining health of the Speaker. He knew the Ghosts were dying and was the first to 'kill' his Ghost. Sending it back to the Traveller. And as soon as he lost his Ghost, he began to die himself. This was when we knew he had been one of the First. One of the first people to be revived by the Traveller, to be a Guardian of Earth.
When the Speaker passed, the Hunters, Titans and Warlocks gathered together where all Guardians once gathered, the City Tower. They all knew they were going to pass as well, all recalling when they had lost their Ghosts. They knew they needed to pass on what skills they could to humans, exo and the dedicated awoken. For the next six months, the Hunter students would learn knife throwing, guerilla tactics in war, effective use of small arms and the skill in silent movement. The Titan students were taught to endure and enhance their bodies to become strong and hardy warriors. They trained in brute force fighting, offense/defense tactics of war and the effective and efficient use of heavy weaponry and CQC weapons. The Warlock students were the most difficult to train as they were to undergo both physical and mental training to be able to tap into the psyche of themselves. Many did not live through these sessions, both Guardians and the upcoming Paladins. They trained in herbology, toxicology and pyrotechnics and in the effective and efficient use of long range weapons and assault rifles. This was the training many passed on. It was the mental training many failed.
The Warlock was sent to the moon, more specifically the Pit of Ash. The new name given to the hole that once held Crota and his minions. It was here they would stay and think. Opening up their mind to the vast dark, the Infinite as it was come to be called. Those who passed these isolated trials would come back enhanced with acute senses and short term precognition. Those who failed often succumb to the darkness and were driven mad, often falling to their deaths within the many traps of the Pit.
When the training was done for the new Paladins, the Guardians had all but withered away, all appearing frail whether it was human, exo or awoken. Humans and awoken were often mistaken for Thrall of the Hive and exo humanoids were but rust and flashing lights. Soon they too passed on and the Paladins were to take the responsibility of protecting Earth.
When the Queen had taken the role of the Speaker, it was then the Traveller made signs of life. When she had held the ceremony for the last Guardians, the Traveller awoke with a low boom, and then a high screech. The combination of sounds was too much for most and many fell in pain as many others saw the departure of the Traveller. It ascended into the sky before vanishing into a flash of light and dust. This was the beginning of the Shadow Age.