Battle of Andoria
The Battle of Andoria was a conflict fought on the outskirts of the Andorian system in 2154. Long-standing tensions between the Vulcans and Andorians escalated into this incident, which involved an attempted preemptive strike by the Vulcan High Command against Andoria. The battle had political repercussions in not only 2154 but also throughout the later half of the 2150s.

Prelude 

In 2154, when the Vulcan High Command learned of the Andorian Empire attempted to steal the second Xindi weapon prototype, Administrator V'Las convinced the High Command that the Andorians were planning to use the prototype to augment their fleet and to create a weapon of mass destruction to use against  – conveniently neglecting to mention that the weapon had been destroyed before the Andorians could make use of it. He proposed that a preemptive strike be mounted to decisively end the threat before it started.

For the preemptive strike against Andoria, the Vulcans secretly amassed a fleet of twelve Vulcan cruisers near Regulus, a star outside the range of Andorian listening posts, while using probes to project false warp signatures near Weytahn. The Andorians were fooled into believing the Vulcans intended to retake the system and committed the bulk of their fleet there. The plan was for the Vulcan fleet to cross the border quickly and, with the element of surprise, quickly capture Andoria, with minimal loss of life on both sides.

However, the Earth starship , informed by Vulcan Ambassador Soval of V'Las' plans, sought out Commander Shran to warn him of the incursion. Shran told Soval that the Vulcan attack would only be met with a massive Andorian counter-strike. The Andorians were only able to gather six warships at the outskirts of the Andorian system to face the Vulcan fleet, with Enterprise joining them in hopes of preventing war.

The combined fleet of Enterprise, four Andorian warships, and two smaller Andorian cruisers faced off against the twelve approaching Vulcan cruisers: four large Vulcan cruisers and eight light support craft. The Andorians were outnumbered two to one, with Andorian reinforcements not due for hours. However, the combined fleet held its ground, depriving the High Command of an easy victory.

The battle 

In the moments before the battle began, Enterprise commander  ordered his ship between the two fleets in attempt to buy the Andorians some time. Tucker contacted the Vulcan High Command to inform V'Las that the Andorians, and Starfleet, were aware of what the Vulcans were planning to do, and recommended that the Vulcan fleet stand down. Undeterred by the empty threat made by Tucker, V'Las warned Enterprise to stay out of the way lest it be fired upon, which Tucker flatly refused to do – since Andoria had come through for Earth in its hour of need a few months before, believing that, with the roles reversed, he owed Andoria nothing less. After making his intentions clear, V'Las cut off communications and ordered his ships to engage the Andorian fleet. 

The Vulcan ships commenced opening fire on the Andorian fleet, and within seconds the Enterprise found itself caught in the crossfire when phaser fire from one of the Andorian ships hit the ship. 

As Enterprise attempted to maneuver out of the line of fire, its sensors detected that one of the Andorian warships was in trouble; its warp reactor had been hit. With a Vulcan cruiser heading towards the Andorian ship, Tucker ordered to have Enterprise fire on the cruiser to draw its attention away from the Andorians. This fact was relayed back to the High Command, whose response was to have the Earth ship destroyed. 

The Vulcan cruiser targeted Enterprise and opened fire on the Earth ship. Enterprise attempted to perform evasive maneuvers, and returned fire, only to find that it was unable to penetrate the cruiser's shields. Just as Enterprise began to be overwhelmed by the cruiser's weapon fire, an Andorian warship, the Kumari, intervened and drew the Vulcan attack back to the Andorians. 

As the battle waged on, the Vulcans continued to target the Kumari and Enterprise. Before long, Enterprise found itself on its own, and nearly removed as a threat by the Vulcans, who managed to take out Enterprises hull plating, disabling its photonic torpedo launchers and helm control, and causing a hull breach on G-deck. Just as the reality of the situation appeared grim for Enterprise, the Vulcan attack on the ship ceased. The battle was over, ending with the withdrawal of the Vulcan fleet.

Revelation and political upheaval on Vulcan 

Meanwhile, on Vulcan, the High Command was monitoring the battle. Minister Kuvak urged V'Las to halt the attack, as even though they were currently winning the battle, they had completely lost the element of surprise and were now facing heavy casualties for both sides in a protracted conflict. V'Las dismissed this out of hand saying "We're already committed." When Kuvak went on to protest that none of the Andorian vessels were outfitted with the Xindi weaponry that V'Las had used as justification for the preemptive strike, but with standard weaponry only, V'Las ordered his guards to hold Kuvak at gunpoint, and shoot if he attempted to intervene again. 

Shran and Tucker were on the edge of destruction, when Captain Jonathan Archer and the Syrrannite T'Pau transported to the High Command and entered with the Kir'Shara, the original writings of Surak. V'Las had already dismissed the artifact as a myth, but T'Pau and Archer (guided by the katra of Surak) were determined that it would reveal the original teachings of Surak from which the High Command under V'Las had strayed. Kuvak, who, upon noticing that his guard's attention was now focused on Archer and T'Pau, had been able to incapacitate him and take his weapon (V'Las attempted to have another High Command member call security, but when told not to by Kuvak, the councilor chose to obey the order given with a gun to back it up) argued that the possibility that it was indeed the Kir'shara should at least be analyzed, but V'Las dismissed the evidence right in front of him, and insisted that the artifact had to be destroyed. Before V'Las could destroy the Kir'Shara, Kuvak stunned him, then contacted the fleet commander and ordered the fleet to withdraw, ending the battle.

Aftermath 
Although from a tactical standpoint the Battle of Andoria was interrupted and indecisive, the political repercussions were greater than most that had occurred in the past century:

 The Vulcan High Command was dissolved and Administrator V'Las was impeached, pending an investigation of charges that he led Vulcan to a preemptive strike under false pretenses.
 With the dissolution of the High Command, a new coalition government was formed headed prominently by the moderate Minister Kuvak, member of the defunct High Command, and T'Pau, surviving leader of the pacifistic Syrrannite opposition movement.
 The new Vulcan government would enter into a less hostile stance with Andoria, ending years of cold war and military tension. Never again would the Vulcans stoop to such a level as using the P'Jem monastery to hide a sensor array for spying on Andoria. This cooling of tensions between the former longstanding adversaries led to a future joint operation, to hunt down a Romulan drone ship, which would have been unthinkable a year beforehand. These events would move Andoria and Vulcan into both joining the Coalition of Planets in 2155.
 The new Vulcan government also took a less paternalistic stance towards Earth. For the first time since First Contact with the Vulcans in 2063, Humans would no longer have the Vulcans holding back more advanced technology and limiting expansion of their exploration of space. For Captain Archer, it was a lifelong dream finally accomplished.
 Though the full translation of the Kir'Shara would take years, as it was finished it would profoundly reshape Vulcan society, helping to return it to the peaceful, logical path that Surak had originally intended for it (see IDIC).
 Unknown to most at the time, the failure of the Vulcan attempt at conquering Andoria, and the direct responsibility of Earth in foiling the attempt, would ultimately lead to grave consequences with the Romulan Star Empire, with which V'Las was secretly conspiring. See Earth-Romulan War.

References 
 
 
 
 
 

de:Schlacht von Andoria
ja:アンドリアの戦い
Andoria, Battle of