I do not own either the Mass Effect series or the Halo series, they are owned by their respective owners.

Hello and welcome to my first Halo x Mass Effect fic I am happy to write this since it's a crossover between 2 of my favorite universes I love the Mass Effect Trilogy even with its ending and I also really like the Halo games (Halo 5 being the exception) this idea has been going around my head since as far back as February but I put it on the sidelines due to other fics and real life but the time has finally come to write this so I hope you enjoy.

2553 March 3rd/2143 CE[1]: The Human-Covenant War official comes to an end after the great schism. The Civilian government is reinstated by the UNSC and the works on rebuilding Humanity are began.

2553/2143 CE April: Civil War erupts on Sanghelios between Covenant believers and the Swords of Sanghelios. UNSC ships arrive at Reach to begin Terraforming.

2553/2143 CE August: Doctor Halsey is reinstated back into ONI service. ONI special forces team arrive on Sanghelios and are ordered to keep the Civil War going.

2553/2143 CE December: The UEG with pressure from the UNSC approaches the Arbiter with a Non-Aggression pact with hopes of technological sharing down the line. The Arbiter accepts the pact as to avoid a possible 2 front war.

2553/2143 CE December 30th: The first UNSC ship arrives at Harvest to investigate if it can be terraformed. They find Harvest glassed beyond any hopes of terraforming it within 80 years.

2554/2144 CE February 12th: a breakthrough is achieved in the shielding technology for ships with the creation of the first human shield generator based on Covenant shielding technology captured over earth back in 2552

2554/2144 CE February 20th: ONI section 3 is tasked with investigating Forerunner technology from the remnants of Alpha Halo and the Ark.

2554/2144 CE March 9th: The Arbiter sends a message to the UEG with a deal detailing the Swords of Sanghelios providing Humanity with technology in exchange for food for his people as the Sangheili face a famine caused by the Civil War and the great Schism. The UEG again under pressure from the UNSC and ONI agree to the deal. Providing the Swords of Sanghelios with Nutrition paste instead of real food until the first crops grown for Sangheili consumption are grown.

2554/2144 CE April: Earth alongside the Inner Colonies are rebuilt with the UNSC navy reaching 5% of its strength before the war, none of its ships are yet to be equipped with Shieling technology.

2554/2144 CE September 1st: Mars experiences a quake revealing a alien construct under the ground. The Area is immediately cordoned off by the UNSC Army and ONI section 3 arrives on scene to investigate. They find out to the dismay of many in ONI that the structure is not Forerunner but are ordered to investigate it further anyway.

2554/2144 CE September 27th: Section 3 finishes the investigation of the Alien structure. They managed to uncover a cache of information in the structures database, they found the race to be called protheans and that they observed humanity for a while before disappearing 50 thousand years ago. The Information cache also held blueprints for an FTL drive and the location of something referred to as a Mass Relay in the Sol system. The FTL method while slightly superior to Human Slipspace drives is limited to Mass Relay and as such mostly rejected by the UNSC. Upon further investigation they also found a Dumb AI in the base center after 5 days of getting information from it the Dumb AI shuts down and all records of the conversation are classified only being told to HIGHCOM and the President of the UEG.

2554/2144 CE November 11th: A Bill suggested by the President is passed in the Parliament increasing UNSC and ONI funding by a margin of 5%. The Construction of UNSC Infinity is accelerated with it receiving Highest Priority followed by its Sistership UNSC Eternity. ONI finds the Mass Relay to be Pluto's mon encased in ice. They activate it and begin the mapping of the space behind it with probes.

2554/2144 CE December 16th: The Existence of the Protheans is revealed to the public and civilian expeditions behind the Sol Relay as it came to be known are authorized.

2555/2145 CE April: ONI detonates a bomb in the Camp of the fighters of the Swords of Sanghelios that were preparing for a raid on the Covenant remnants leaders' location, killing majority of the fighters there.

2555/2145 CE June 19th: Following the Bombing of his forces the Arbiter asks the UEG for help once again requesting it provide fighters for his side in exchange for military technology. Humanity refuse but instead propose military equipment to be provided to the Sangheili alongside an increase of food export. The Arbiter accepts.

2555/2145 CE August 9th: The first planet behind the Mass Relays is colonized, named Eden prime after its almost Earth like ecosystem. The UEG increase the budget of the UNSC once again allowing the UNSC to begin construction of new Ship classes. The Essex-class Fleet Carriers[2], the Preston Cole-class of Battleships[3], the Bastion-class of Heavy cruisers and Medusa-class of Destroyers.

2556/2146 CE April: The first hull of the Essex-class and Preston Cole-class are laid down over Mars. UNSC Essex and UNSC Preston Cole are planned on joining the Home Fleet upon their completion.

2556/2146 CE December 24th: ONI documents leak to the public leading to the Civilian Population and the UEG government to learn of the actions undertaken by ONI prior and during the Human-Covenant War. Mainly the Spartan II, Spartan III projects alongside the Assassination of several important Human figures aswell as instigation of the Insurrectionist Movement.

2557/2147 CE January: Its hand forced by the UEG and the threat of another Civil War if nothing happens UNSC forces are forced to detain the leadership of ONI and seize its assets.

2557/2147 CE March: UNSC HIGHCOM, the UEG Primeminister and key ONI heads meet in secret to discuss the apropriate responce to the outrage against ONI. Admiral Parangosky, Admiral Osman alongside the heads of Section 0,1 and 2 agree to take the fall and take responsibility for the actions. The Head of the secretive Section 3 Admiral Jack Harper is chosen by Parangosky to become the commander of ONI. Shanxi becomes the 2nd Planet to be colonized withing the Mass Relay network. 2nd Essex-class Carrier and Preston Cole-Class are laid down intended for the 2nd fleet. UNSC Ticonderoga and UNSC Eisenhower.

2557/2147 CE April 8th: UNSC Infinity enters service under the command of Captain Laskey. UNSC Navy starts equipping their ships with Shielding technology.

2557/2147 CE December 9th: Colonists on Shanxi discover a crashed space ship filled with weird eggs, they report it to the authorities. The UNSC Military on Shanxi go on full alert and the 2nd Fleet is dispatched to Shanxi.

2558/2148 CE January: The Biological Warfare unit of the Marines is sent in alongside ONI teams inside of the ship to investigate it and recover the eggs. They start investigating the computers found on the ship.

2558/2148 CE April: First colonists arrive on Reach. They set up a settlement in the unglassed northern portion of the planet. The shipyards above Reach are being Rebuild

2558/2148 CE August 8th: UNSC Spirit of Fire arrives at the Ark to a surprise to many in the UNSC who thought the ship to be lost with all hands. The ship is boarded where they find the rampant ship AI which is promptly shut down. They find the crew in cryosleep. The ship is recovered and moved back to earth and the crew awakened.

2558/2148CE August 18th: Celebration is held for the crew of UNSC Spirt of Fire in denying the Covenant access to weapons that could have wiped out Humanity. Captain Cutter is promoted to Rear Admiral for his service after he chose to remain in the Military.

2560/2150CE March 7th: ONI manages to gain access to the Crashed ships computers and find out the Eggs and the Ship belong to a race called Rachni that were involved in a war but didn't survive. The Eggs are the eggs of a queen and her guards. ONI wants to hatch the eggs but are denied by Jack Harper. HIGHCOM and the current President are once again briefed on what happened and the information classified.

2560/2150CE September 1st: UNSC Eternity Enters service it is assigned to the Home fleet. The 3rd Essex-class and Preston Cole-class are laid down, UNSC Enterprise and UNSC Jeanne D'arc respectively. They are supposed to join the 5th Fleet upon completion.

2560/2150 CE December 31st: The yearly population report is submitted. Eden Prime has reached a Population of 10 Million and is chosen as the capital of the Colonies in the Mass Relay network. Shanxi reaches a population of 3 Million.

2563/2153 CE May 2nd: UNSC Essex and UNSC Preston Cole enter service in the Home Fleet. The Sight of the New ships show many on earth how far the UEG and UNSC has come. 80% of the UNSC Navy is equipped with Shields.

2564/2154 CE May 2nd: UNSC Ticonderoga and UNSC Eisenhower enter service with the 2nd Fleet.

2565/2155 CE January: Work begins on Eden Prime Shipyards as to ease the strain on the Mars shipyards and the recently rebuild Reach Shipyards.

2565/2155 CE April 1st: ONI teams are deployed on Shanxi and Eden Prime to abduct children that were born with weird masses around their spine. They manage to abduct the children and ONI section 3 starts research.

2565/2155 CE November: With the Civil War entering its 12th year the Arbiter is desperate for it to end and asks the UEG for assistance. The UEG agrees after UNSC assures them that if push came to shove, they could take on the remaining Sangheili Ships. The 2nd Fleet is ordered to move and assist the Swords of Sanghelios

2565/2155 CE December: What came to be later known as the Sanghelios offensive involved the frigate and destroyer escort of the 2nd fleet going into orbit and preforming a low yield Mac bombardment on covenant positions in preparations for Marine and Swords of Sanghelios forces attack that followed right after the bombardment concluded. While a controversial move and one that the Sangheili disapproved of, it destroyed key fortifications preventing a successful breakthrough from happening without huge losses. On the 26th the entire remaining covenant Fleet jumped into system and engaged the 2nd Fleet and the Fleet of Glorious Retribution. Admiral Kastanie Drescher and Vice Admiral Steven Hackett earned the respect of the Sangheili Fleetmaster Rtas 'Vadum with unconventional Tactics that ended in the destruction of the Covenant fleet on the 30th.

2566/2156 CE January: The assault on Sanghelios continued with the pocket closing further and further on the remaining Covenant forces on the ground. A Final assault is planned but before it can be executed the covenant forces preform a suicidal assault on the UNSC and Swords of Sanghelios lines on the 20th. The assault takes many by surprise and causes heavy casualties on the UNSC and SoS side pushing them back before managing to stop the covenant forces on the 29th.

2566/2156 CE February 19th the UNSC and SoS forces launch an all scale attack on Covenant locations bringing in again frigates for tactical bombardment and large-scale mechanized spearhead attacks that break through the strong defenses of the Covenant forces. Lieutenant Anderson of the 8th ODST brigade manages to take the covenant leader Jul 'Mdama prisoner when he and his squad were dropped into the covenant HQ. That evening Covenant forces were in full retreat and at morning the next day surrendered. Marking the end of the Civil War on Sanghelios.

2566/2156 CE February 28th For his service Vice-Admiral Hackett is promoted to Admiral and put in charge of the 5th fleet. Lieutenant Anderson is promoted to Lieutenant Commander for his actions in capturing the Covenant leader. Following his action, the N7 program is launched its task is creating highly specialized and lethal Special Forces teams. Anderson is chosen as the first candidate for N7 training.

2566/2156 CE October: The SoS is reformed into the Sangheili Sovereignty with the Ungoy, Kig-Yar and the Lekgolo joining them for protection. The Arbiter chosen as the leader approaches the UEG with a request for an Alliance which the UEG accepts. Spartan-class Battlecruiser is designed and 5 Hulls are immediately laid down with more being planned.

2566/2156 CE November 7th: The Spartan V program is launched, aiming to be more efficient like the Spartan II program but as large as the Spartan IV program, All UNSC service members are checked if they meet the requirements for the program and so far, only 500 have been found.

2566/2156 CE December 31st: A new Mass Relay is opened leading into a system with yet another perfectly colonizable garden world. This sparks concern in the UEG and UNSC as every mass relay they have opened so far led to either systems rich in minerals and Element Zero or to a Garden World named Elysium. The opening of new Mass Relays is prohibited and patrols in the Mass Relay colonies increased. The Yearly population report is filled. Shanxi reaches a population of 10 Million. Eden Prime reaches a population of 20 Million

2567/2157 CE February 8th: UNSC Enterprise and UNSC Jeanne D'arc enter service in the 5th Fleet. UNSC Graf Zeppelin and UNSC King Arthur are laid down they are supposed to enter service in the planned 13th Fleet.

2572/2162 CE April: The 2nd Fleet is relocated to the Eden Prime; it is supposed to act as the fleet responsible for the defense of the Mass Relay colonies. Work also begins on Arcturus Station[4], the only system leading into the Sol system by the use of Mass Relays.

2572/2162 CE May: Plans are drawn up for a new Fleet Carrier and Battleship. The Everest-class Fleet carrier and the Avery Johnson-class Battleship. 2 of each Hulls are immediately laid down as the construction of the Essex-class and Preston Cole-class are being halted after the 5th ship of the class leave the shipyards. UNSC Everest and UNSC Avery Johnson are designed to join the 8th fleet while UNSC Kilimanjaro and UNSC Jacob Keyes are joining the 9th Fleet. The Sirta Foundation the inventors of Biofoam invent Medi Gel, it is quickly adapted by the Military and civilian sector.

2572/2162 CE July: The Citadel Council creates an exploration fleet tasked with mapping out the Skylian Verge and surrounding systems. UNSC HIGHCOM is briefed that so far 1000 Individuals have been found and volunteered for the Spartan V program and that the N7 special forces are numbering in at 2000 Members reaching the N2 rank with only 200 Completing the N7 training. The construction of the 13th Fleet also begins.

2574/2164 CE June: UNSC Graf Zeppelin and UNSC King Arthur enter service with the yet incomplete 13th Fleet. The Last hull for the Essex-class and the Preston Cole-class are laid down. The 5th and last vessels are called UNSC Formidable and UNSC Julius Cesare.

2574/2164 CE July 10th: Fleet Admiral Lord Terrence Hood passes away in his sleep a ceremony is held for him and his service to the UEG and UNSC. He is Replaced by Admiral Kastanie Drescher as the head of the Navy and the defacto head of HIGHCOM

2574/2164 CE December 31st: The Eden Prime shipyards are completed and immediately start pumping out ships for the UNSC Navy as well as private use. The Yearly population report arrives and Eden prime has reached 35 Million while Shanxi has reached 19 Million. The Economic Report also arrived showing a increase in mineral and heavy metal production leading to cheaper metals used for Military use. Increasing the amount of mining and military jobs by 6 million leading to an economic boom as all other sectors expanded due to the 2. Arcturus Station is 10% complete

2576/2166 CE January: Citadel Expedition have found a dextro World which is colonized by the Turrians later on after finding the Quarian fleet trying to set up a colony there and the Turian 30th Patrol fleet having to force the quarians to leave.

2579/2169 CE August 5th: The Citadel Exploration Fleet arrive at their last objective Relay 314. In their 7 years they have uncovered 9 garden worlds 2 of which were dextro based 3 were given to the asari and 3 were given to the Salarians while the last one was given to the Batarians. Relay 314 is opened and the Exploration Fleet jumps.

2579/2169 CE August 7th: …

Being chosen for the task of leading a citadel exploration fleet would be a great honor for everyone it was a great experience. But being stuck for 7 years on the same job quickly lost that prestige and it became mondain. Only finding garden worlds for colonize and no new Civilization like many hoped they would. Matriarch Benezia however knew why she was chosen for this job; it was to get her to stop being a metaphorical thorn in the very real ass of the Matriarch council. But even if the task was mondain and she knew the real purpose of her job at least Benezia was happy that her daughter was allowed access to the freshly discovered prothean Ruins that Benezia found on her mission.

Today was the day her mission would end and she would be back to throwing a wrench into the plans of the Matriarchs back on Thessia. Relay 314 while being the last Relay in the that they were supposed to investigate it gave them much trouble refusing to open many times until the Salarians finally managed to make the relay think that the master command from the Relay hub came to open. She had to give them credit it was a nice trick. They had to wait a day before the ice on the other side cleared as was Citadel regulation. And they were now on their way into the new system. "How much longer till we make it?"

"2 Minutes Matriarch"

"Good when we drop out I want scanners up immediately and start making preparations if we find any planets for ground based exploration"

the same officer replied "Yes matriarch" and moved over to a console.

2 Minutes came and went and they dropped out of FTL the bridge crew immediately went to work doing as Benazia commanded. "Matriarch, Captain Tiberius is hailing us"

"Patch him through" the officer nodded and did as he was ordered. The Face of a Turian appeared on Benezia's screen. "Yes captain what is it ?"

"Matriarch, orders came through, in 3 days we will have to stop protecting your ships, we have been ordered to rejoin the 27th Patrol fleet. A destroyer will come to replace us in a week" of course just at the last system the turians had to turn back. Something was off, then returning through all the now opened relays with no protection was just begging to be attacked by pirates

"I understand Captain, thank you for your protection of me and my ships" the Turian nodded and disconnected. The bridge returned to the silent humming off engines and the pinging of consoles as the crew kept scanning. For a moment at least because not even a full minute after she had disconnected the Captain, the sensors officer spoke.

"Matriarch, we have found a garden world in the system" "that's great then bring us in further" "we cant matriarch"

"why is that ?"

"there are over 120 ships in orbit of it. 100 are heading our way as we speak"

"Ships? What kind of ships?" "from the looks of it, Warships, the largest being 5.2 Kilometers long." Asari normally had blue or purple complexion, but Benezia was white at this moment and she wasn't the only one everyone on the bridge also went pale or stared in disbelief.

She stared with her mouth open at the senor operator and didn't notice the incoming hail from the Turian cruiser that served as their escort. After a moment she regained some of her composure and answered the hail "Y- Yes captain?" she said in a shaky voice the captain was arguing in the background

"What do you mean they just disappeared? Matriarch, we have to get out of here now !"

"We cant captain we have made first contact, escaping could be viewed as a aggressive move" "Matriarch, they are sending 100 warships our way, 2 of which are super dreadnaughts longer then the destiny ascension I do not care if its first contact or not, at this moment the safety of the entire expeditionary fleet is my most important objective and I am ordering you to retreat."

Benezia's sensors officer yelled "4 cruisers just jumped between us and the relay, we are cut off !" Benezia looked back at the captain who also received the same information. Even if he was a turian, he wouldn't pick a fight with 4 cruisers while he only had 1 cruiser at his disposal. Now he would listen to her and let her talk their way out of here.

"Looks like we aren't going anywhere captain, now let me handle this and maybe we will have a new race on the citadel soon." The captain begrudgingly accepted and disconnected. "Communications, transmit our first contact package on all frequencies" the communications officer nodded and did so.

Now came the hard part of waiting in anticipation and horror as the 100 ships encircled the small exploration fleet. 2 hours of waiting later her communications officer perked up "Matriarch, we are being hailed, video and audio" Benezia swallowed a lump that was in her throat and accepted the hail, she was going to meet these new aliens, when she came back the matriarch would eat from her hand.

[1] I Chose CE to mean Council Era but in reality, its just the Mass Effect Timeline so for example if we take the Mass effect Reaper invasion happened in 2186 so technically speaking it would take place in 2186 CE

[2] Essex-class Fleet Carrier

Length: 5,225 meters

Height: 752 meters

Width: 661 meters

Armor: Titanium-A3 4.5 Meters

Shielding: 2 Series 102 mk.2 Hahn-Kedar energy shields


- 1 Miniaturized SMAC

- 300 Archer II Missile pods

- 150 Rapier Missile Pods

- 30 Onager MAC cannons dispensed across the whole ship length with 15 on each side

- 900 CIWS PD Gatling Guns dispensed across the whole ship length with 450 on each side

- 100 AA Guns dispensed across the whole ship length with 50 on each side

- 4 Avenger Class Nuclear devices.

- 120 Lance Missile systems with 60 on each side.


- 8000 Navy personnel

- 600 Marines personnel

- 200 ODST personnel

Ariel Vehicles:

-300 F-45 Katana Multi Role Fighters.

-50 D79-TC b Pelican Dropships

-75 Longswords

-250 SOEIV drop pods

[3] Preston Cole-class Battleship

Length: 5,290 meters

Height: 790 meters

Width: 620 meters

Armor: Titanium-A3 5.5 Meters

Shielding: 2 Series 102 mk.3 Hahn-Kedar energy shields


-2 Miniaturized SMAC aligned under each other at the front

-2 Cruiser sized MAC cannons aligned on each side of the SMAC

- 350 Archer II Missile pods

- 225 Rapier Missile Pods

- 60 Onager MAC cannons dispensed across the whole ship length with 30 on each side

- 800 CIWS PD Gatling Guns dispensed across the whole length with 400 on each side

- 80 AA Guns dispensed across the whole ship length with 40 on each side

- 8 Avenger Class Nuclear devices

- 200 Lance Missile systems with 100 on each side


- 7800 Navy personnel

- 600 Marines personnel

- 200 ODST personnel

Ariel Vehicles:

- 25 F-45 Katan Multi Role Fighters

- 10 D79-TC b Pelican Dropships

- 250 SOEIV drop pods

[4] Arcturus Station is a new Arcturus class station designed to act as a naval anchorage and a sector administration station. Standing at 10 Kilometers in length 1.5 Kilometers in Height and 2 Kilometers in width it is protected by 10 ODPs and a small fleet of 1 Battleship 8 Heavy cruisers 2 Light carriers 20 destroyers and 60 frigates. So far it is the only Arcturus class station in existence.

UNSC Navy in 2579:

13 Main Fleets with each fleet having between 90-150 ships

15 Patrol Fleets each with a cruiser at its head ranging between 20-30 Ships

6 Quick Response Forces each with a Battlecruiser at its head ranging between 50-70 ships.

Home Fleet with UNSC Eternity at its head with 250 or more ships depending on the situation.

4 Reserve Fleets with a battlecruiser at its head with 70 ships (Only active during Wartime or during times of high tension)

20 Flotillas permanently stationed at points of interest each with a cruiser at its head ranging between 30-40 ships

Each colony has a defense fleet the smallest defense fleet being 2 destroyer and 6 Frigates. A Defense fleet can contain up to a battlecruiser and 2 cruisers.

More fleets are in service in the UNSC Navy but arent included in here due to their homogeneous use.

2 Infinity-class Supercarriers

5 Essex-class Fleet Carriers

5 Preston Cole-class Battleships

2 Everest-class Fleet Carriers (Being Build, supposed to be finished by 2580 with more being planned)

2 Avery Johnson-class Battleships (Being Build, supposed to be finished by 2580 with more being planned)

15 Spartan-class Battlecruisers (Last 2 are being build, supposed to be finished by 2581)

*Edited because i wrote down the wrong date for half of the years