AN: Someone told me that I would need a timeline, and quite frankly for future planning, I have decided to give you all just that. I hope you enjoy the timeline, and know that there are lots of major spoilers here. Just FYI. This will also mildly be a multiverse crossover since I threw the Aliens series in. I've always found that series and Halo to have uncanny resemblances.

March 10th, 2080: The humans of Earth finally advance their technology enough to reach for the stars and begin colonizing other planets. Mars was the first, followed by the Jovian moons and other close worlds followed.

June 15th, 2160: The bitter Jovian Moons campaign ended, resulting in the collapse of the Unified German Republic.

December 21st, 2163: United Nations marines ambushed communist troops at Argyre Planitia and defeated them. While it showed the marine's effectiveness in combat, it showed that to keep the peace, a space-military organization representing Humanity's strength was required. Thus, the United Nations Space Command (UNSC) was created.

June 10th, 2180: A UNSC starship, the USS Sephora, is sent out to investigate the distress signal from another UNSC ship, the Sulaco, which went missing weeks before. Only 100 marines returned home, their ship destroyed after they were ambushed by mercenaries hired by the infamous Weyland-Yutani company, which was immediately dissolved once their actions reached the public. Even a new alien species was claimed to be discovered, but they were wiped from the forever desolate world of LV-426 before these claims could be investigated.

May 31st, 2182: All ship-assigned androids were considered obsolete, and scrapped. After experimenting with another retired company's revolutionary product: the first Artificial Intelligence, AIs were created and replaced the android's position on all starships.

January 20th, 2291: Humanity invents the slipspace drive, creating faster-than-light travel.

April 12th, 2310: It was official that Earth was overpopulated and over militarized. Using the newly created Shaw-Fujikawa Slipspace drive, colony ships were mass produced and even more worlds were colonized, giving birth to the Inner Colonies.

August 11th, 2490: Around 800 planets were colonized, ranging from mighty fortresses to tiny settlements. The Inner Colonies were the political and economic strongholds, although materials from the Outer Colonies were essential.

January 6th, 2506: It had become apparent that a massive rebellion against the UNSC was on the verge of occurring. The Office of Naval Intelligence attempted to quell the rebels, now dubbed the Insurrectionists, by creating the ORION Project, or the Spartan-I program, to create real super soldiers and using the most advanced military technology possible. However, expectations were not met and the ORION Project was canceled and their agents were transferred to other military fields of the UNSC.

September 14th, 2517: As a result of the failure of the Spartan-I Project, Dr. Catherine Halsey created the Spartan-II program to create the ultimate soldiers who would assist the UNSC in ending the Insurrection.

October 31th, 2524: A civilian freighter from Harvest, Horn of Plenty, encountered a Covenant ship. Despite Humanity's attempts to make peace with the aliens, the Covenant and UNSC fought on Harvest, and the UNSC lost. The Human-Covenant War had officially begun.

November 5th, 2525: Dr. Halsey used biological augmentation on her original 75 recruits for the Spartan-II program after years of training, but only 33 survive and as standard armor, they are given the newly invented Mjolnir Mk. IV armor.

January 2nd, 2536: Taking inspiration from the II's, the Spartan-III program was set in motion.

August 10th, 2536: The Covenant destroyed most of the UNSC Outer Colonies and began making their way into the Inner Colonies.

August 20th, 2552: No matter how hard the UNSC fought, the Covenant fought and managed to capture Reach within days and glass its surface.

August 22nd, 2552: The events at Halo Installation 04 occur. John-117, the Master Chief and Cortana, picking up any survivors of the attack and hijack a Covenant ship, heading to Reach and return to Earth with surviving Marines, Spartan-IIs and Dr. Halsey. They discover the largest ever seen Covenant fleet preparing to invade Earth and despite one of the Spartan-II's sacrificing their very life, the fleet is destroyed and delay the invasion of Earth.

August 23rd, 2552: The survivors return to Earth and warn the UNSC of the imminent invasion.

August 30th, 2552: The Battle of Earth begins.

August 30th, 2552: Master Chief finds Delta Halo, kills the Prophet of Regret and after uniting with the Arbiter, fight for their species' survival. In the process, Arbiter kills the Brute's chieftain Tartarus and prevent the ring from being fired.

December 12th, 2552: The Battle aboard Halo Installation 00, the Ark, occurs. Master Chief activates Halo 04B with a rescued Cortana's help and wipes the Flood from Earth. As a result of the firing before the ring could be stabilized, the Halo becomes unstable and blows up the ring and the Ark at the same time.

March 3rd, 2553: After decades of fighting, the Human-Covenant War ends. Over 25 billion humans lost their lives in the war and heavy losses for the other races occurred as well. Humans and Sangheili sign a peace treaty, uniting the 2 species. Humans start to break the glass on every former colony worlds and returning the planets to what they were like before their glassing as well as create the Spartan-IV program.

April 5th, 2553: The Swords of Sanghelios government was set up on Sanghelios. They discover that several small factions who hold on to Covenant beliefs are on Sanghelios and the Urs System.

June 10th, 2557: These factions of the former Covenant unite into the Covenant Storm, led by Jul 'Mdama. The Swords of Sanghelios engaged them in another war, with help from the UNSC.

December 1st, 2557: The Covenant Storm gained access to the Forerunner shield world of Requiem with the Master Chief's presence, despite his fighting against them.

December 2nd, 2557: The Storm awaken the Diadect, the last living Forerunner imprisoned on Requiem millennia before by the Librarian. He allied his Promethean forces with the Covenant and retrieved the Composer. In the end, he was killed by the Master Chief, but not before Cortana "died."

February 5th, 2558: UNSC and Covenant forces battled over control of Requiem, which ended in the world's destruction.

November 20th, 2558: Prometheans from Requiem betray the Covenant, allying themselves with Cortana and her goal to rule the galaxy. Only when Fireteam Osiris, led by Spartan Locke, and Blue Team, led by John-117, joined together, defeating Cortana and destroying most, if not all the Prometheans.

December 5th, 2558: In a large-scale battle between UNSC and Sangheili forces against Jul 'Mdama's forces around Earth in their attempt to capture the Infinity, the Covenant Storm's complete destruction resulted. Dr. Catherine Halsey betrayed the Covenant and killed Jul 'Mdama, but not before wounding her heavily. Before her death, Dr. Halsey gave John-117 the Covenant's half of the Janus Key. With Thel 'Vadam and Lord Terrence Hood at his side, he completed the Janus Key and unlocked the Absolute Record.

January 10th, 2559: Thanks to the Absolute Record, the UNSC and Sangheili started searching for Forerunner artifacts and setting up research facilities for experimenting with Forerunner technology, the most famous facility being the one on Halo Installation 07, led by famous human scientist Luther Mann. All new Spartan-IV teams were trained and equipped with the greatest technology and now they became tougher fighters than ever before, even the older teams were greater than they once were.

March 5th, 2560: After a year of peace, the UNSC and Sangheili agreed to use the Forerunner technology to massively advance their own technology and decided to begin a massive overhaul production of military hardware and grow their standing armies to the billions, out of paranoia another war like the Human-Covenant War will occur. Negotiations with UNSC colony worlds that somehow survived the Human-Covenant War and fell out of communication also began.

April 10th, 2580: After many years of peace, aside from the occasional Insurrectionist attack, the UNSC has returned to where they were before the Human-Covenant War, and their hardware was more advanced than before. Few human worlds, such as Mamore, had been unpleasant with their negotiations but most had agreed to return to being members of the UEG. Terraforming worlds for both humans and Sangheili had gone much smoother than either had expected. The other species returned to their normal lives and while they occasionally live in Sangheili colonies, most remained on their home worlds.

March 15th, 2582: Every outlet in the galaxy, both UNSC and Sangheili, received a transmission from an AI designated Epsilon about a long forgotten UNSC world called Chorus and the great UNSC war heroes who were on the planet. Charon Industries were run out of business as a result, and their chairman, Malcolm Hargrove, was given a life sentence in a maximum-security prison.

October 19th, 2582: The UNSC come in contact with the planet of Chorus, and despite the negotiations being a little rocky, the UNSC agreed to help the Chorusans reestablish order on their world, build a new capitol city, new fortresses and cities, as well as allow the Chorusans to keep every single piece of Forerunner technology on their planet in exchange for joining the new government setup of the UEG.

January 2nd, 2583: Present time.