Battle of Ceti Alpha V

The Battle of Ceti Alpha V is a battle between the remnants of humanity and the Xindi in 2165 of an alternate timeline.

Prelude
In 2153, while chasing the Xindi weapon, Captain Jonathan Archer is infected with interspatial parasites while trying to save the life of T'Pol. As a result of the amnesia the parasites induce, Archer is rendered incapable of commanding the and the Xindi destroy the Earth in 2154. The remnants of humanity, around 6,000 people, eventually settled on Ceti Alpha V while the Xindi hunted the galaxy for them.

Determined to cure Archer, Doctor Phlox spent the next twelve years searching for a way. After learning that the only existing way to destroy the parasites would be to vaporize Archer in a subspace implosion, Phlox worked on developing his own treatment and came up with an antiproton beam powered by the Enterprise's warp core. The first use of the beam eliminates one of three clusters of the parasites in Archer's head in both the present and on all of the previous scans taken by Phlox. Phlox and T'Pol come to realize that if they eliminate all of the parasites in the present, they will be eliminated in the past too, potentially altering the timeline for the better as Archer would never have been infected and could conceivably lead the Enterprise to victory over the Xindi.

Before the treatments can resume, the Enterprise captures a Yridian spy who had informed the Xindi of the location of the remnants of humanity. Needing all power for the weapons, Captain Tucker ends the treatments and shortly afterwards, six Xindi ships are detected entering the system. 

Battle
The engages the six Xindi ships with phase cannons. Though the ships return fire, the new shields, provided by General Thy'lek Shran hold. The Enterprise breaks off and is followed by an Insectoid and a Reptilian ship while the rest head for the planet. As the two ships chase the Enterprise, they are attacked from behind by the Intrepid and another starship, disabling the Insectoid ship. The Enterprise then focuses its fire on the Reptilian ship, knocking out its engines. The defeat of their two ships causes the four remaining Xindi ships to alter course to engage the three defenders.

Under heavy attack, the Enterprise manages to destroy an Insectoid ship, but starts taking damage itself with forward shielding going down to 52%. An Insectoid and Reptilian ship target the Intrepid together, blasting off its port nacelle. With no other choice, Trip orders them to retreat. The Enterprise then loses phase cannons to a hit. The forward shield then collapses and the Enterprise suffers hull breaches on B and C decks. With the forward shields down, the Xindi ships target the bridge and blast the top off of it, killing the Enterprise bridge crew.

As boarding parties beam aboard the Enterprise, T'Pol orders Phlox to meet her and Archer in Engineering to complete his treatment since destroying the interspatial parasites will alter the timeline. In Engineering, Phlox discovers that the chamber used in the treatment has been destroyed by debris and is unusable. Archer remembers Phlox telling him that the parasites can also be destroyed by a subspace implosion which will destroy the Enterprise as well, but they don't have another choice.

Archer orders T'Pol and Phlox to flee in a shuttlepod while he overloads three plasma injectors to create the implosion since the Xindi are only looking for humans, but both refuse. Discovering that one of the injectors has been damaged, Archer sends Phlox to get a replacement from a supply locker which he uses to successfully replace the damaged injector. Overcoming nearby security teams, Xindi boarding parties enter Engineering and kill Phlox. T'Pol starts setting up the implosion as Archer lays down covering fire but is killed before she can finish. Archer takes over, setting the controls on the warp core as he exchanges fire with the Xindi, taking several hits. With the last of his strength, Archer manages to trigger the subspace implosion moments before dying. The subspace implosion consumes the Enterprise, destroying the ship, its crew, the boarding parties and the parasites.

With the Enterprise gone and the Intrepid forced from the battle, the Xindi presumably win and destroy the last of humanity. 

Aftermath
As hoped, the subspace implosion destroys the interspatial parasites in both 2165 and 2153, resulting in Archer only suffering a concussion and no amnesia. Without the amnesia, Archer is able to remain in command of the and lead humanity to a different conclusion to the Xindi incident.