DISCLAIMER: I DO NOT OWN HALO OR STAR WARS, THEY BELONG TO 343 INDUSTRIES AND DISNEY.
So I though I'd do a Halo star wars crossover, next chapter is a codex about the UNSC/UEG and Swords of Sanghelios while the Galactic Republic stays the same except for its amount of Warships, I'll give you a hint: it will be in the millions. Reviews are appreciated! Also the UNSCs shipyard capability is drastically increased and its colony number to 923 along with rest of the Orion Arm and what's behind it so about 30,000 planets at leastalthough there could be up to 800 million stars in the Orion arm so it could be around 400 million although the UEG does not own them, yet, and they will later on in the story. :)
Timeline
2020-2494
Yeah no, not gonna bother with that piece of timeline as its the exact same as Canon.
2494-2525
The Insurrection takes place
2525-2553
Humanity comes in contact with an alien collective called the Covenant who declare war on Humanity as the Covenant Prophets current goals include wiping Humanity off the face of the Universe as they are seen as an affront to their God's.
Human-Covenant war begins.
The UNSC sends the famed Vice Admiral Preston J Cole to with a fleet of 78 Warships to retake the agricultural colony of Harvest, the battle ends with 39 UNSC ships in ruin and 36 in need of repairs, this includes the UNSC Everest, the flagship of Vice Admiral Cole and a Covenant ship.
2526
Preston Cole retakes Harvest at the cost of 142 UNSC ships and 89 Covenant.
2527
The Covenant glass 8 systems and 29 planets.
2528
The UNSC assembles the a Fleet of over 390 Warships and gave them to Admiral Cole and told him to deal as many losses to the Covenant as possible while it evacuates the Outer Colonies and fortifies the already well defended inner colonies as well as Earth and creates several fortress worlds in the outer colonies to make sure that the huge Battle-Group Everest can resuply and add even more ships to it.
Arcadia is one of these fortress worlds along with Rose and Collective.
2529
Battlegroup Everest destroys 3 Covenant shipyards and 4 refuelling stations meaning that the Covenant has been delayed by about a year due to travel distances and being less able to attack UEG planets.
2530
The Covenant destroys the Rose defence Fleet and glasses the planet below at the cost of 423 ships of various classes and 632 UNSC ships, the biggest defeat in the war yet. The UNSC can't replace these ships for over 2 years.
2531
The Covenant forces Battle-Group Everest after they retook Harvest to retreat to Arcadia with its remaining 59 ships and follows in pursuit with over 900 to to kill Cole as he has destroyed over 2000 Covenant ships.
Arcadia is glassed with 532 Covenant ships destroyed and 232 UNSC.
(Events of Halo Wars take place)
2532
The UNSC commissions the SPARTAN-III Project.
29 UNSC systems are captured along with 82 planets glassed.
2533
The UNSC deploys a NOVA bomb to the Covenant colony of Gerric vav'.
The casualties range In over 3 billion in total.
2534
The UNSC discovers a Forerunner ship under Castle base and starts to study it.
Mystery increases when it is discovered that the Forerunner terminals react and open up to Human touches.
Dr Halsey starts to study the ship and reverse engineer the technology.
2535
The UNSC loses 521 ships trying to destroy 3 CSO super carriers before they get an escort fleet to protect them.
2536
Collective is attacked but the offensive is repelled by 701 UNSC Warships, 23% of the remaining UNSC fleet.
The UNSC suffers 321 ships as they attempted and succeeded in capturing a CAS class assualt carrier.
The Office of Navel Intelligence sends scientists to reverse engineer its energy shields and slipspace drive.
2537
Energy shields are adapted of off the Forerunner ship but are considerably weaker and can only survive a direct energy projector beam for 2 seconds or 4 plasma torpedoes before failing.
3538
The UNSC is pushed off Collective but not before leaving a NOVA bomb in the deapest mine and destroying the planet so that no UNSC technology can be studied along with destroying 309 Covenant ships.
2539
The UNSC opens the hanger of the Forerunner ship and discovers over 300 Despair-Class-Hunter-Killers or Forerunner fighter and immediately starts trying reverse engineering its propulsion, its inertial damperners and shielding so that they can install them on the new Sabre class fighter.
7 more planets fall to the Covenant.
2540
The UNSC starts to fortify the inner colony of Boomstick, it will have 42 SMAC ODPs to defend it, along with 309 UNSC ships that have been refitted with shields.
The Covenant system off Heysa giese' is destroyed by a new design of NOVA bomb, it does what its called and has enough fire power to destroy an entire system 2 times the size of the Sol System (Our solar system)
2 more planets fall to the Covenat
2541
The UNSC makes a break through on the CAS class assualt carrier that was captured back in 2536.
ONI and UNSC scientists discover the schematics for the slipspace drive and recreate it using Titanium-A, (the material that is used on the Hull of UNSC Warships) this slipspace drive can go 901 light years per day, a blessing compared to the UNSCs former drives that could only go 2.6 light years per day.
The scientists immediately go to helping the others study its energy shielding to install on all UNSC ships, just hearing Admiral Parangonsky the 2nd most dangerous Human alive show up and congratulate them and then tell them to "Make sure every Goddamn UNSC ship has the energy shielding of a CAS class assualt carrier so that the world is a better place for Humanity" made scientists get to work after having a nice days rest and preparing to study it.
Estamations show that they will have CAS class energy shielding by 2547.
2542
The UNSC finishes fortifying Boomstick and it begins to build ships to add to the dwinderling numbers of the UNSC navy.
2543
ONI starts to design new warships to integrate the CAS energy shields and its weapon complement along with the new Sabre fighters which start construction once the design has been finalized.
ONI notices that a CSO class super carrier is being built, ONI deploys 22 SPARTAN-IIs to capture it see if they can reverse engineer the shields to equip on some of the new ship lines including the Strident class heavy frigate.
Battle of Psi Serpentis
2544
The UNSC Infinity begins construction at special assembly plant Concord located in the Sol Systems oort cloud.
2545
The UNSC successfully tows the CSO back to Onxy using 3 punic class supercarrier after 2 years of searching for self destruct buttons and tracking devices.
2546
ONI takes 1 of the 4 remaining punic class super carriers for testing new Forerunner and Covenant technology.
The first inner colony is destroyed.
2547
ONI reverse engineers the magnetic fields that keep the plasma in place and uses this to tip their Archer missiles and MAC cannons with it to bring down Covenant energy shields faster and then causing damage to the Hull.
ONI finds a Forerunner research stations coordianates from Onyx, ONI sends a Prowler but it is at the other side of the Galaxy so it will take 79 days at least to arrive.
2548
The Covenant find out about the captured CSO class super carrier and try to find out its coordianates.
The next 9 inner colonies are destroyed.
2549
The Office of Navel Intelligence finnaly makes a breakthrough with CAS and successfully reverse engineers the energy shields and make the generator out of Titanium A.
All UNSC ships are being recalled to be refitted with these new energy shields.
3 more inner colonies are glassed.
2550
The UNSC makes its first conventional offensive strike against the Covenant and destroy a major refuilimg Station on the edge of the outer colonies.
4 more UNSC inner colonies are glassed.
2551
The UNSC is down to its last 1000 ships
200 are set to come out of the shipyards by 2552
200 ships are deployed to Reach while 400 are deployed to Earth while the rest are scattered around the colonies.
The 900 ODPs around Earth still haven't come online, they are set to finish in September 2552.
The UNSC claims a jackals gauntlet shield and reverse engineers it into full personal energy shields, this is only given to Spartans.
2552
The Covenant find Reach, the UNSC suffers 122 ships destroyed while the Covenant suffers 938 ships including the Long Night of Solace, a CSO class super carrier that gived even the unmoving SPARTAN-IIs a second thought, although it is destroyed by Jorge-052 at the cost of his life.
Reach is held.
The Sabre class space superiority fighter is is a success and it begins mass production.
Events of HALO COMBAT EVOLVED.
Events of HALO FIRST STRIKE.
The Covenant discovers the location of their CSO and head to the planet only to find a Forerunner shield world and 98 UNSC ships and 32 ODPs.
The events of HALO GHOSTS OF Onyx (the CSO is destroyed as well)
The Covenant attacks Earth with 13 CCS class battle cruisers and 2 CAS class assualt carriers
The UNSC Home Fleet destroys the ships at the cost of 12 of their ships and 2 ODPs, effectively piercing a hole in the defence grid.
Events of Delta Halo/Installation-05
The Prophet of Truth attacks Earth with is Forerunner Keyship and activates the portal to the Ark and attempts to fire the Halo array.
EVENTS OF HALO 3
2553
A treaty is signed between Lord Hood and Thel Vadam' to sign the end of the of the Great War.
Infinity is finished
The UNSC starts researching Hard-light weapons and shields.
2554
The UNSC Strident class frigate, Anlace class frigate, Izanagi class destroyer, Autumn class heavy cruiser, Warlock class super-heavy-cruiser, Titan class battle-cruiser, Vindication class battleship, Posiden class light carrier and F41 Broadsword enter service.
2555
The UNSC Infinite begins construction.
The UNSC starts designing the Eternity class Supercarrier. (Go onto Halo Fanon and look at Titan class dreadnought, it looks like that)
2556
The UNSC returns to the abandoned outer colonies that weren't found by the Covenant.
2557
Master chief is found.
The Didact is awakened on the shield world Requiem, an proceeds to attack Earth, the UNSC Home fleet proved useless against the Forerunner flagship: Mantles Approach, Sierra-117 hijacks the ship after Infinity blasts through the Didacts shields and he flys through the hole and defeats the Didact at the cost of his long time friend and AI companion: Cortana.
2558
The Didact is once again found on Halo Installation-03, he kills Spartan Black team, before 117 kills him along with Blue team by ejecting the control room into a planet.
Spartan ops take place.
2559
Dr Halsey is rescued by Fireteam Osiris.
ONI finds out about the greater galaxy and 2 factions called the Separatist Alliance and the Galactic Republic and begrudgingly shares the information with HIGHCOM and they immediately task ONI with finding out more information to tell the UEG senate.
2560
The UNSC Destiny, a Strident class frigate, comes in contact with a Republic Venator looking for a Separatist providence class dreadnought, the Venator attacks the UNSC ship thinking its a new type of Separatist ship, the Strident is destroyed but not before it blows off the bridge of the Venator with MAC cannon shot and and gets a distress message on the ALPHA-01 Frequency to CINCONI with classified material while the shipboard AI got part way through hacking the Venators computers while simultaneously setting the all 12 Havoc tactical nukes and 38 Shiva Nuclear missiles to detonate if the Venators sends troops to board it.
Later, Anakin Skywalker arrives in Resolute alongside the Zarich and the Ratish.
When Skywalker sends troops to board the ship the ship suddenly explodes destroying the original Venator and Zarich while crippling the Ratish, the Resolute is only EMP'd by the blast.
2561
The Lord Hood reveales the information to President Ruth Charet who had continued to be President even though her terms have ended however the UEG senate pressed for her to be kept in office due to her goal to make Humanity the dominant species in the Galaxy!
The President told the UEG senate and pushed for full mobilisation to prepare for WHEN the next attack came, everyone in the senate knew that it was an IF certainly not a WHEN.
Serin Osman is the new CINCONI after Margaret Parangonsky retired
The ONI prowler that was sent to the Forerunner research station is discovered to be a Warfare Research Facility, due to the crew being Reclaimers, the monitor is very compliant.
When the crew returns to UNSC space, they bring the monitor back with them, it introduces itself as 094 Light bulb and it gives ONI the schematics for Forerunner and Ancient Human slipspace dirves, Hard-light weapons and the Ancient Human glassing beam.
Humanity will not interigrate this technology until they fully understand it and know how to replicate it.
The UNSC Infinite is complete.
Construction on the UNSC Eternity begins.
2562
The Republic returns to UNSC space which is on the edge of known space bordering the Unknown Regions.
The UNSC, which is prepared for War, sends the 1st fleet, consisting of the UNSC Infinite 29 Autumn class heavy cruisers, 234 Strident class Frigates 122 Izanagi class destroyers, 42 Posiden class light carriers and 12 Warlock class super heavy cruisers.