Yesterday's Enterprise timeline

When 7 Romulan Warbirds, led by General Volskiar, attacked the Klingon Outpost on Narendra 3, the Enterprise-C, under the command of Captain Rachel Garrett, recieved the distress call and came to help, though it was able to destroy 2 of the Warbirds, it ultimately succumbed to battle damage.

In this timeline however, the Enterprise-C disappeared in the middle of the battle with the Romulans into a Kerr Loop Rift in time which had been formed by the constant weapons fire between the Enterprise-C crew, the Romulans and the Klingons. After the battle, the Klingons who salvaged Narendra 3's data recorder from the ruins naturally assumed the Enterprise-C "fled in shame" and reported this to their superiors. This degraded the already tenuous peace negotiations and ended up in an all out war 2 years later. After 20 years of constant fighting, the Klingons were on the verge of victory (as half of Starfleet was destroyed and Federation officials believed surrender was 6 months away, but this was not made public).

Tasha was born on Turkana 4, where she had to constantly evade rape gangs, thieves and murderers on a daily basis to survive. Eventually she escaped the planet and joined Starfleet's Security Corps, to help with the Second Klingon-Federation War. She was fortunate enough to become chief tactical officer aboard the first Galaxy-class Warship; the Enterprise-D, under the command of Captain Jean-Luc Picard. With her assistant; the ship was able to score many victorys for the Federation, such as at Archer 4, but not enough to turn back the tide of the Klingons.

Tasha was made aware of her true fate in 2366 when the Enterprise-C emerged from the Kerr Loop Rift's second aperture. She was told by her friend Guinan, that her true death was "empty and without meaning". She couldn't accept this and was allowed a transfer to the Enterprise-C, which was still critically damaged and only had a skeleton crew of 125 (out of 700) and was now commanded by Lieutenant Richard Castillo; her new friend and lover. The ship then re-entered the rift and history was restored.

Sadly, Tasha's wish for an honourable death were ultimately unsuccessful; as though they were able to destroy another of Volskiar's Warbirds, the ship was disabled and 10 Enterprise-C crewmembers (including Tasha and Castillo) were captured by the Romulans from the ship just before it exploded.

While in captivity aboard Volskiar's flagship; the Victorious, Castillo was murdered trying to protect Tasha from the guards; Tasha was deeply saddened by his death. Meanwhile, her beauty was noticed by Volskiar himslef and she made a deal with him to allow the surviving Enterprise-C crewmembers to live in exchange for Tasha staying as Volskiar's consort. She however secretly planned an escape while on Romulus and bided her time to get everything ready. This plan was initially hampered however when she became pregnant and gave birth to Volskiar's daughter, Sela, a year after the deal was made.

4 years later; her plans were ready and she made her escape from the planet, however, she cared too deeply for Sela to be left behind and took her with her as she left Volskiar's compound. This however proved to be a fatal mistake as Sela had no wish to leave and alerted the guards. Tasha was found and killed in front of Sela, leading her to consider humanity a weakness.