This summary is consisted of information provided by the various Terminals scattered throughout Halo 3. Every one of these facts have written evidence to support them (Couldn't quote all of them, too much). The Terminal's story starts near the end of the Forerunner-Flood war, it also give fragmented information about important events during the Halo firings. All the bold text represent the theories I have about the subject at hand. Remember, some pieces of information are missing from the Terminal, this is the best I could do to piece all of Halo puzzle together. There are clues about the mysterious planet at the end of Halo 3 legendary, keep reading and find out.
The Forerunner are currently at war with a biological parasite -better known as The Flood. Events prior to the activation of the Halo installations have been recorded and archived within "Terminals" scattered throughout the Ark and other such facilities. The Forerunners considered themselves to be the guardians of life in the galaxy, they observe and protect all those who they were under their wings. They follow some sort of legend or myth (perhaps their religion?) that believe in the protection of all living things. As the Forerunner took guardianship over worlds and species, the races under them became more dependant upon their abilities, this is also the cause of their downfall. "Can't you see? Belief in the Mantle sealed our doom! Weakened our [protectorates, bred dependence and sloth. Our [so-called Guardianship has stripped those we would keep safe of any capacity for self-defense!" .
For three hundred years the Forerunner have waged war against the Flood, they are slowly losing the war against the parasitic foe. With each world consumed by the parasite, the Forerunners are forced to pushed back their lines (the [Maginot sphere, similar to the Dyson sphere of some sort the encompasses a major section of the inner galaxy) -sometime even abandoning unaffected worlds. Understanding that the parasite were a foe to be reckoned with, the Forerunners built the Halo installation as a "last resort" weapon. The Halo installations (also known as the Halo Arrays) were scattered through out the galaxy and possessed a massive super weapon and when all seven rings are activated it is capable of wiping out all sentient life forms in the blast radius. With the line slowly being pushed back, the Forerunner began indexing (or storing data) about the sentient species that exists beyond and within the line. THEORY: The Index used to activate the Halo installations contains the DNA/Species genetic code that the wave pulse will target, anything that has not been included will survive the blast . During the conflict, the Halo installations on the other side of the line could be activated without wiping out the sentient species inside the line. The Liberian states that "I'm close to finishing the task. The indexing and the archival processes are as complete as I can hope for. If we wait longer, we risk catastrophe. The thing has already destroyed every colony on my side of the line. Please. Activate the Array." to which the Didact replies, "No. Activation is murder. A genocide larger than [this galaxy has ever known. We are sworn to protect life not destroy it! That is the Mantle we were given to carry.". It seems that the Forerunner's belief in protecting all living things morally prevented them firing the Installations while there are living things still on the other side of the line.
As more worlds are consume under the massive Flood onslaught, the Forerunner began a desperate campaign against the Flood. Believing that destroying the hive mind would end the parasitic problem, the Forerunner created the construct Mendicant Bias to lead them in the campaign to destroy the central mind. Using whatever left of sentient life forms left on the other side of the line as a necessary sacrifice, the Forerunner baited the Flood into feeding on the remaining worlds to buy them time to rebuild their forces. Taught to believed that the Flood is an aggressor race, the AI Mendicant Bias finally came into contact with the Flood's central hive mind. Influenced by what the Hive mind told it and believing that the Flood was the next evolutionary process, Mendicant Bias states to the Hive "I was created to study you as if you were some problem to solved. And I have done so [379,907 hours. If they wished they could have made a decision based on that data alone. But as you are the next stage in the evolution of the universe, who am I – or my creators – to obstruct your progress?" and it began to believe that the Forerunners "choose to remain beholden to ancient myths does not matter where they claim their authority originates obstructs the path of universal evolution and must be removed. No matter how well intentioned, their obstinacy in the face of the inevitable progression of nature can no longer be tolerated.". Instead of a great tactical asset, Mendicant Bias betrayed the Forerunner and sided with the Flood. The betrayal of Mendicant Bias tipped the war into the Flood's favor, thanks to Mendicant's knowledge of the Forerunner's plans. Ceasing it's feeding, the Flood change their course and headed to assault the Forerunner's line. "Something is wrong! It's moving away! At night I can see it – flitting shadows – black against the stars. Thousands of ships! Not spiraling outward but heading for the line. This is the tipping, Didact. It's no longer feeding. It's coming for you.". Understanding that they will lose the war, the Liberian taken the liberty "to remotely destroyed our Keyships (Same as Truth's ship". A security measure. Without them I cannot reach the Ark. But neither then can the thing. I'm trapped. On a beautiful, empty, world.(Earth) Its inhabitants have been safely indexed, every single one of them. They're special – well worth the effort it took to build one final gateway, even at this late hour." Instead of expanding outward and consuming all in their path, Flood launched a counter attack (or a Preemptive strike). "We've confirmed your observations. Infected supraliminal ships are arrowing inward from several clusters. No more spiral growth. The thing is counterattacking. Suppression, Security and Emergency Circumstance fleets are all being recalled. Systems are evacuating. Mendicant Bias is no longer communicating with us. "
With the aid of Mendicant Bias, the Flood fleets are able to gain access into the line, "Contender AI 05-032 // Mendicant Bias is returning and has the capacity to bring the enemy through the [Maginot sphere". As the Flood fleets pushed inside the Forerunner lines, the Forerunner high command began a scorch earth policy (denying enemy tactical resources or position). "If we start immediately – commence total biosphere elimination of life sustaining worlds (as indicated in the accompanying charts) and relocate evacuated populations to facilities such as those described in the [Onyx project – all this could be achieved in [57,1590 (+ or – 2,1842) hours."
THEORY: "Follow-up report from the Primary Pioneer Group (hereafter: PPG) is [173 hours delinquent. Report [G617ak/g/postlandfall seemed most promising: a planet capable of supporting life located within the near border region of the [galactic halo with no indigenous sentient species. The section indicating no fauna of any kind shall be considered anomalous until verified by Advance Survey Team – Alpha (hereafter: AST-A) team leader [[?. If confirmed, that fact alone would justify the dispatch of an investigative group to [G 617 g. If neither the PPG nor the AST-A have delivered a follow-up report within the next [333 hours this office will have no recourse but to send a medium intensity military exploratory detachment to determine the exact nature of the previously mentioned delinquency."
If this document is true to it's word, the Forerunner sent a military exploration force to this habitable planet that is "near border region of the [galactic halo with no indigenous sentient species". If the events of which Halo was activated during the task force was investigating the planet, some Forerunner may have survived. (Definitely not Earth, considering Earth is in Delta Halo's weapon radius, maybe...the planet at the end of Halo 3?)
During the entire war, the Forerunners have fought the war in "Half-measure", it would later mean that the Forerunners didn't fight the Flood to the fullest extent. Bound by their Mantle, they Forerunners strive to protect all living things, even if that means losing the war. An example is that if faced with a Flood invasion of a strategic factory planet with civilian population, they would rather abandon it rather than killing all the innocents. In the last few years of the war, they finally threw always those protocols and began to "follow the Flood in their footsteps". Burning and destroying all infected planets that they come across, but they were already too late. The parasites have spread to far and wide. Understanding that there is no way to win except for total annihilation, they Forerunners accept genocide that they were about to commit. [b 05-032 is Mendicant Bias's Serial Number [/b "05-032 was right about one thing: there is only one way to defeat the enemy, and that is to visit utter annihilation on it. If the galaxy must be [rendered temporarily lifeless. So be it. As Mendicant stated in its report [58.078:H 48:M 12:S ago: half measures will not suffice. " During the final battle between the two fleets, one commanded by a Offensive Bias and the other by the traitorous Mendicant Bias the Halo Arrays was finally activated. Though the crew of both fleet has perish, the two AIs fought a final battle against another by remote controlling the ships that is placed under their control. "The [Halo effect strikes our combined fleets. All ships piloted by biological are now [adrift. I can trade Mendicant ship for ship now and still prevail.". Thanks to the fact that most of Mendicant Bias's ship were piloted by the Flood, they became combat ineffective after the activation of the Halos. This allowed Offensive Bias to outnumber MB's fleet and defeated him. "05-032 abandoned the tactic of using derelict ships as cover after [72:S – It seems that 52 core vessels lost to the ruptured fuel cells of derelict ships was lesson enough. Add another 608 lost to collision, point fire, structural failure due to inertial manipulation, and [slipstream space induced discoherence and I now outnumber Mendicant [6:1." and "[00:H 03:M 00:S Mendicant was able to postpone its inevitable annihilation for [106:S with its attempt to flee. But the last of its core vessels hangs before me now; crippled and defeated but still sensate. I could spare it; carve out what is left of its [personality construct array and deliver it to [Installation Zero for study. I doubt it would have extended the same courtesy to me."
With the activation of the Halo Arrays, all sentient life forms in the galaxy has been eradicated. Only dust and echos remains. Though the Forerunners have won the war, they traded everything they had so that we may have a future. We may not be the direct decedents of the Forerunners, but we inheritor of all their technologies, and...their sins.
"[Father. I hope this message finds you well and helps you understand my decision. Today I leave the only world I have ever called home, not for glory or [the anomalous desire to end another's life[? as you have [indicted: but to [travel the path of demons[? to spare the hands of [another Father's son. "Had we acted sooner; had we acted more decisively…" Living in the past is a luxury none of us can afford. We must learn from it, but we cannot live there. It is impossible to plan for the [now – the present is ever fleeting. [The future is where we must live – [the future is what we must plan for. I do not look to trade my life in order to preserve our past, but to secure the future – and if not ours, then the future of some [culture yet to come. Isn't sacrifice in the interest of others what you spoke of as being so noble? Should I have allowed another to bloody his hands while I remained safe behind a [shield of privilege? You raised me better than that."
" Proud? When I have failed you utterly, how can I feel anything but sorrow? Bias has come undone. He crossed the line this morning – brought the abomination with him – and destroyed your waiting rescue party. It's over. We're activating the [destructive arrayed matrix, our shameful last resort.
I can picture you in your garden surveying all you have created – surveying all you have preserved. And I curse the circumstance that keeps my finger on the trigger. Of all the fates to befall us, this is the cruelest of all. My inaction and hesitation and foolishness kept me here, on the wrong side of the Line. And [300 years [? of our society's failure and miscalculation makes me your executioner. Its too much to bear.
// ERROR – NO CARRIER OR RECEIPT AVAILABLE DEAD END TRANSMISSION (Halo Activated while this message was transmitted to the Liberian)
//INFORMATION DESTROYED IN TRANSIT
Mendicant Bias is trying to prevent us from firing the Array. He speeds back to the Ark, but he won't succeed. Offensive Bias will stop him, and I will burn this stinking menace in your name. And then? I will begin our Great Journey without you, carrying this bitter record. Those who come after will know what we bought with this [false transcendence – what you bought, and the price you paid."
All the Terminals documents have been carefully selected by Mendicant Bias for you (Master Chief) to view. It shows all of his actions, all his mistakes, and he seeks atonement for what he has done.
"You don't know the contortions I had to go through to follow you here, Reclaimer. I know what you're here for. What positions do I take? Will I follow one betrayal with another? You're going to say I'm making a habit of turning on my masters. But the one that destroyed me long ago, in the upper atmosphere of a world far distant from here, was an implement far cruder than I. My weakness was my capacity – unintentional though it was! – to choose the Flood. A mistake my makers would not soon forgive. But I want something far different from you, Reclaimer. Atonement. And so here at the end of my life. I do once again betray a former master. The path ahead is fraught with peril. But I will do all I can to keep it stable – keep you safe. I'm not so foolish to think this will absolve me of my sins. One life hardly balances billions. But I would have my masters know that I have changed. And you shall be my example."
THEORY: The Halo installations have been activated during the evacuation to Onyx, (explains why there are no Forerunner inside the shield world). It should be noted that Onyx was a project. I believe that Onyx was one of a kind, the one and only shield world in existence.
THEORY: We humans have been archived and indexed by the Forerunner, maybe all of the Indexed/Archived species are considered to be reclaimers such as we are.
THEORY: The Ark cannot support a sustained life on it, it an artificial world, maybe all the Indexed beings are sent there and stored, waiting for someone to come along to "replant" them upon the worlds.
THEORY: Remember, the librarian destroyed all of HER Keyships. In Halo 3 we learned that Truth's Dreadnaught was actually a Keyship for activating the portal to the Ark. Someone or something made it on the Keyship and got through the portal...after the activation they came back out from the Ark and began to spread the speeds of life again.
All the quotes are directly from the Terminals, word for word. I been hearing about people complaining that Halo 3 doesn't "Finish the Fight", in fact Halo 3 instead tells us "about the fight". Stop being lazing and playing the game on normal, pick legendary and look for the hidden Terminals. That's where all the answers lie. BTW: This is not my best writing, its more of a bunch of notes cobble up and held together by duct tape.