Prologue
"They're flanking us!"
"Watch out for those rockets!"
"Incoming!"
"They're breaking through!"
Cybertron was dying. There was no disputing that, not when the Energon was running dry, not when rust was overtaking the cities, and certainly not when the AllSpark itself had been sent off-world. Already, swathes of Cybertronians were fleeing the planet, whether they were taking part in the war or not. And now, the war had come to Iacon. Most of the city had already fallen; all that was left was the Command Center. And the Autobots who remained were fighting tooth and nail to hold back the Decepticon legions.
All but the main entrance had been sealed off, forcing the Decepticon forces into a bottleneck. Holding the door was what was left of the Autobots, led by Ultra Magnus and the Wreckers. He stood alongside Leadfoot, Roadbuster and Topspin, gunning down enemy after enemy, reinforced by Autobots Cliffjumper, Sunstreaker, Elita-1 and Chromia. Seekers who attempted to attack from the air were gunned down by the Decepticon defector Jetfire, who had switched sides several orbital cycles ago. Though they were slowly being worn down, the Autobots were standing firm against their attackers.
Inside of the Command Center, Ratchet and Wheeljack worked alongside Sentinel Prime to finish bringing the experimental Space Bridge online. It was their only hope of getting offworld at this point, and they were running out of time. The other Autobots were working to download as many files as they could before deleting them from the Command Center's computers, as well as setting explosive charges to destroy the building behind them. They couldn't afford to allow anything to fall into Decepticon hands. In the Space Bridge chamber, Optimus Prime rushed in with Ironhide and Bumblebee, and joined the Autobots Arcee, Bulkhead, and Smokescreen - the soldiers chosen to form Team Prime, a unit to guard the Matrix of Leadership once they fled Cybertron.
"Team Prime, gather your weapons and supplies. The Space Bridge will be ready soon enough, and we will need to depart swiftly." Optimus' orders were followed instantly, and as the Autobots rushed to complete their tasks, the young Prime made his way over to his mentor, Sentinel. The elder Prime looked to Optimus, and said grimly, "Our darkest hour is upon us, young Optimus. But you will give us hope with your survival. I will remain behind and hold off Megatron and his horde. Keep the Matrix safe at all costs, understand?"
As Optimus nodded, there was a yell, followed by a muffled explosion. Ultra Magnus and the Wreckers ran in, sealing the doors behind them and setting up one final layer of defense. Sentinel moved to join them, drawing his double-ended sword and shield, saying, "Commander, report." Ultra Magnus saluted, and said solemnly, "We lost Cliffjumper, Sunstreaker, Chromia and Elita-1. I ordered Jetfire to retreat; he's moving into orbit to escape. He'll rendezvous with us when he can."
At that moment, the Space Bridge sparked to life, opening a blue-green portal.
Sentinel gave a nod to Optimus, who called out, "Autobots, roll out!" Team Prime all ran through the portal, disappearing in flashes of color. Sentinel then looked to Ultra Magnus and said, "Go. Take the Autobots, and go into the underground tunnels. Get to the Xantium; these three and I can draw the attention of Megatron long enough for you to escape." The Autobots all rushed to follow their orders, and Sentinel turned to the Space Bridge. He raised his shield, and it transformed into a powerful cannon. He fired at the Space Bridge controls, disabling the device, though not destroying it. At that moment, the door exploded inward, and the Decepticons came pouring in.
At the head of the horde was Megatron himself, snarling as he fired his fusion cannon at Sentinel while the Seekers Starscream, Dreadwing and Skyquake attacked the Wreckers. The Autobot and Decepticon leaders traded blow after blow, the Prime slowly giving way to the Gladiator of the Pits of Kaon. Around them, the Wreckers each succumbed to the Seekers, and Starscream fired a missile at Sentinel. The Prime blocked the explosion with his shield, but left himself open to Megatron, who grabbed Sentinel's sword and used it to impale the Prime through the Spark. As the Prime died, Megatron taunted, "What was it you said? One shall stand, one shall fall? Indeed, today you fall!"
Soon, the room was silent as Soundwave and Shockwave joined the Decepticons, and immediately began to work on repairing the Space Bridge. Megatron turned to face the Decepticons, and raised a fist in victory. "Cybertron is ours! Sentinel Prime is dead! Today marks the beginning of the end of the Autobots!"