|Location of Event :
||Delphic Expanse 
|Year of Event :
||2153 - 2165 
|Nature of Event :
||Alternate Timeline 
The NX-01 Enterprise spent much of 2153/2154 searching the Delphic Expanse for the Xindi in an attempt to prevent them from launching a massive attack on Earth. The Expanse was at this time filled with spatial and other anomalies; when one of these hit the ship Captain Archer was badly injured. Doctor Phlox discovered that he had also been infected with several clusters of parasites which had the effect of preventing him from forming long term memories. Despite searching for months, Phlox was unable to find any cure. The parasites originated from a realm beyond normal space-time, making them impossible to treat.
Since Archer was unable to function as Captain, Starfleet granted Subcommander T'Pol a field commission and appointed her captain. She continued Archer's mission, eventually locating the Xindi weapon. Unfortunately, the Xindi attacked Enterprise and the ship was badly crippled. The damaged ship was unable to reach the weapon in time, and Earth was destroyed.
The Xindi subsequently attacked every Earth settlement they could find; eventually only 6,000 Humans remained alive. The few survivors settled on Ceti Alpha V; T'Pol resigned and settled there with Archer in 2156, leaving Tucker in command of Enterprise. In 2165 Doctor Phlox visited the planet and announced that he had finally discovered a treatment for Archer's parasite infection. The procedure required energy on a scale which could only be generated by a warp-capable starship, namely Enterprise.
Onboard the first cluster of parasites was successfully removed, but Phlox noticed an amazing effect; the parasite was gone not only from the new scans he made of Archer, but from all previous scans as well. Since the creatures exist outside of normal space-time, destroying one removed it from the whole of history. T'Pol and Phlox realised that if all the parasites could be removed from Archer, he would never have suffered from his condition. History would be changed, perhaps even to the extent that Earth could be saved after all.
Unfortunately, the Xindi finally managed to track down the Ceti Alpha colony by having a Yridian follow Phlox there. They launched a fierce attack, inflicting massive damage on Enterprise. T'Pol, Phlox and Archer headed to engineering to create a subspace implosion in the warp core - something which would destroy the ship and everybody on board, but which would also destroy the parasites. With Xindi boarding parties roaming the ship, Phlox and T'Pol were both killed in firefights but Archer managed to initiate the implosion.
The plan worked; the preferred timeline was indeed restored, with no sign of parasite infection in Archer.