The Battle of Veridian III was a confrontation between the Galaxy-class USS Enterprise-D, which was then the Federation flagship, and a renegade D12-class Klingon Bird-of-Prey. The conflict took place in very close proximity to Veridian III, in 2371.
The Bird-of-Prey's involvement in the engagement was in revenge for previous affairs with the Federation. Although the Enterprise would have easily outmatched the Bird-of-Prey under normal circumstances, the crew of the Klingon ship exploited a key weakness in the Enterprise's defenses and was thereby able to inflict severe damage on the opposing starship. The Enterprise eventually managed to defeat the Bird-of-Prey, but the Enterprise's victory was a Pyrrhic one, as its battle damage led to (but not unavoidably so) the additional loss of the ship soon thereafter. (Star Trek Generations)
After the House of Duras fell from power at the end of the Klingon Civil War of 2367-68, the Duras sisters, Lursa and B'Etor, sought incessantly to regain supremacy and take control of the Klingon Empire. (TNG: "Redemption", "Redemption II", "Firstborn"; DS9: "Past Prologue") To this end, they forged an alliance with Doctor Tolian Soran in 2371.
On an inspection of the Amargosa observatory by Lieutenant Commanders Data and La Forge, Dr. Soran assaulted La Forge and captured him, transporting himself and La Forge to the Duras sisters' ship. The craft set a course for the Veridian system while Soran removed and analyzed La Forge's VISOR. The Enterprise subsequently pursued and intercepted the Bird-of-Prey. Although Soran ordered the destruction of the Enterprise, B'Etor pointed out that their ship was completely outgunned by the Galaxy-class starship.
Soran decided to return La Forge's VISOR to him, after performing some modifications to the device, which gave Lursa and B'Etor a live video feed from La Forge's point-of-view. Since it was vital that Captain Picard try to negotiate with Soran, he agreed to exchange himself for La Forge, on the condition that he could speak to Soran – who was now on the surface of Veridian III – first, and in person. The Duras sisters accepted this proposal and returned La Forge to the Enterprise while Picard was transported to Veridian III.
When La Forge returned to engineering, the video feed from his VISOR gave the Duras sisters exactly what they had been looking for. A freeze-frame revealed that the Enterprise's shields were operating on a frequency modulation of 257.4 megahertz. Preparing for the Bird-of-Prey to attack the Enterprise, B'Etor directed that the frequency of the Klingon ship's photon torpedoes be adjusted to match, then delightedly moved a scope into place. (Star Trek Generations)
The battle Edit
The engagement commenced when the Klingon Bird-of-Prey fired a couple of consecutively deployed photon torpedoes at the Enterprise. These projectiles easily penetrated the Starfleet vessel's shields, impacting on the flagship's secondary hull.
As the Enterprise started to rotate starboard, the ship returned fire using phasers, but the resultant impact had no effect on the Klingon ship, being stopped by the Bird-of-Prey's shields. The Klingons retaliated by firing a disruptor blast at the Enterprise.
The Klingons' return fire caused an explosion at one of the starboard stations on the Enterprise's bridge. This sent an officer who had been manning the station flying to the deck and showered debris over the conn officer, severely injuring both members of personnel.
Under orders which Commander Riker then issued her, Commander Troi, the Enterprise's counselor, took the conn officer's place and brought the Enterprise out of orbit, but the ship was suffering a hull breach on decks thirty-one through thirty-five.
The Enterprise slowly backed off from its attacker, completing its rotation away from the Bird-of-Prey. Even so, the Klingon vessel persisted with its onslaught, as the Enterprise's wounded crew members were being carried off the ship's bridge. Though two pairs of disruptor shots fired from the Bird-of-Prey missed their target of the Enterprise's hull, a third struck the ship's port warp nacelle.
Amid the fracas, Commander Riker asked recently promoted Lieutenant Commander Worf about the Bird-of-Prey and its weaknesses. Worf was able to identify the ship as a D12-class Bird-of-Prey, explaining it had been retired from service due to defective plasma coils. Without seeing how the defect could be used to their advantage, Worf pointed out that the coils formed part of the ship's cloaking device.
In main engineering, another eruption knocked another crewman down. La Forge, who was working there at the time, responded by issuing orders to the other engineers.
On the Enterprise's bridge, Data informed Riker that, if a low-level ionic pulse were to be targeted at the Bird-of-Prey's plasma coils, it might reset the coil and engage the cloaking device. The shields would meanwhile drop, leaving the ship vulnerable for just a few seconds. Data, in full support of the plan, began work on the pulse.
Aboard the Bird-of-Prey, the helm officer reported to B'Etor that their ship's shields were continuing to hold. B'Etor responded by ordering the crew to fire at will.
Onboard the Enterprise, Riker instructed Worf to ready a spread of photon torpedoes and target the Klingon craft's primary reactor, also reminding Worf that they would have only one opportunity to make their plan work.
The Bird-of-Prey fired at least three more pairs of disruptor bolts. The first two passed straight through the Enterprise's shields without hitting the ship. Thus, only the last volley had any effect, striking the Enterprise's starboard nacelle.
Data was just about to set off the ionic pulse when the Enterprise's bridge received its biggest blow yet; just after Riker ordered him to hasten the ionic pulse, a blast which consumed the aft stations in smoke and debris also thrust an officer across the room's wooden handrail, sending him tumbling over the command stations before he landed on the deck. Despite the disruption, Data finally managed to activate the pulse.
Savoring almost imminent victory, the Duras sisters (with B'Etor still operating her scope) ordered their crew to target the Enterprise's bridge with full disruptors. Instead, the Bird-of-Prey's shields dropped and its cloak began to engage, much to the surprise of the Klingons. The Enterprise then fired a single torpedo that hit home on the Bird-of-Prey, completely destroying it. (Star Trek Generations)
The outcome of the battle, immediately afterwards, brought a sense of joy to the bridge of the Enterprise. An officer standing behind the wooden handrail made a fist, with his left hand, then victoriously pummeled the air with it. Apparently without noticing this action, Data did likewise, excitedly exclaiming, "Yes!"
Even though the Enterprise had destroyed the Klingon vessel, damage to the magnetic interlocks caused by the Bird-of-Prey led to a coolant leak in the warp core, causing an imminent warp core breach aboard the Enterprise. On Riker's instruction, a saucer separation was therefore carried out, with all personnel evacuated to the saucer section. The warp core detonated sooner than expected, though, leading the saucer section to crash-land on the surface of Veridian III. The ship was subsequently determined unsalvageable and declared destroyed, but casualties were light. The remaining crew was recovered by the USS Farragut, as well as two other starships, shortly thereafter. (Star Trek Generations)
The deaths of Lursa and B'Etor reduced the House of Duras to just one effective member, Toral. He later made an ultimately failed attempt to gain control of the Klingon Empire by claiming the Sword of Kahless. (DS9: "The Sword of Kahless")
Background information Edit
In the first draft script of Star Trek Generations, the battle was fought between the Enterprise-D and a Klingon battlecruiser rather than a Bird-of-Prey, and there was no scope described being used on the Klingon ship in either that draft nor the final draft of the movie's screenplay. However, in the latter, the Duras sisters' vessel had been changed to a Bird-of-Prey. 
Early in the development of Generations, the screenplay's writers – Ronald D. Moore and Brannon Braga – intended for the Battle of Veridian III to have a different outcome than it does in the film's final version. A couple of drafts of the film's script, including the first draft of the screenplay, established that Riker and other surviving crew members from the Enterprise, following the crash-landing of the ship's saucer section on Veridian III, discovered that Lursa and B'Etor, as well as some officers from their Bird-of-Prey, had not only survived but had also ended up on the same planet. (audio commentary, Star Trek Generations (Special Edition) DVD/Blu-ray)
In the first draft script, the engineers from the Enterprise had begun to salvage what they could of the ship's components and a group of parents and children had been let out of a hatch on the side of the vessel's saucer section – supervised by Riker, La Forge, and Worf – when the Klingons, having gotten to their craft's escape pods in time, attacked, unseen, from inside the Veridian jungle. They shot phaser fire that struck against the hull of the Enterprise's saucer section, destroying equipment and sending all the ship's survivors rushing for cover. Worf and Riker returned fire with their own phasers. Under orders from Riker, La Forge started to hurriedly lead the children back inside. A pair of security officers rushed outside but one of them was instantly shot dead. The other took up a position on the ground near Riker and Worf. They continued to exchange fire with the still-unseen Klingons until the hidden assailants stopped firing a few seconds later; though La Forge was uncertain why they had stopped shooting, Worf speculated that they may be attempting to set up a different line of fire. Riker took a chance by approaching the Klingons unarmed, and, as he had hoped, negotiations with them then began.
Both groups were now marooned on the planet and the Klingons demanded they be given a shuttlecraft from the Enterprise, Lursa even threatening to shoot down the shuttle if it launched without them. Finding their terms unreasonable, Riker considered, in a meeting of the Enterprise's senior staff, if a deflector shield could be rigged to protect the shuttlecraft from the Klingons' assault, but doing so wouldn't be easy from a technological standpoint. Thanks to Data seducing the Duras sisters in a violent mating experience that took place off-screen, both crews were eventually able to put aside their differences enough to collaborate on finding a way off the planet (first using the shuttlecraft, with Lursa and B'Etor onboard, to collect Captain Picard).
The story continuation featuring the Duras sisters surviving was never produced, being vetoed from the script for Generations long before principal photography on the film began. (AOL chat, 1998) Rick Berman, who co-wrote the movie's story and produced the film, later explained that the scene had to be cut from an overly long draft of the screenplay and was edited out on the recommendation of David Carson, who persuaded the rest of the producers that it was a good idea to do so. (The Making of the Trek Films, UK ed., pp. 158-159) B'Etor actress Gwynyth Walsh once implied that she believed the reasoning for the sequence's removal was that the writers had a massive variety of characters they had to service in Generations, including the entire collection of main characters from Star Trek: The Next Generation and Captain Kirk. (Star Trek Monthly issue 36, p. 38) Furthermore, Lursa actress Barbara March mused that the sexy appearance of the Duras sisters may have contributed to their downfall, admitting, "That might have been a continual problem, I think, on that kind of show [....] We didn't really seem to kick that much butt, and I think they decided it was just time to kill us off. I don't think that the writers, who did generic kind of villainnesses, understood what it was like to be a Klingon female." 
Industrial Light & Magic was assigned to create the visual effects footage used in depicting the Battle of Veridian III. The sequence challenged ILM to devise a strategy of representing the conflict with a bare minimum of shots and no budget for pyrotechnic elements. (Cinefex, No. 61, p. 74) Neither did the allocation of expenses allow for breakaway models. (The Making of the Trek Films, UK ed., p. 168) The final moments of the altercation were storyboarded in pencil by Bill George, during planning discussion with John Knoll. Knoll created computer-generated storyboards showing the start of the action. (The Art of Star Trek, pp. 284 & 285) Even though the battle was inspired by the Star Trek space battles depicted in the television series and the earlier films, Knoll also endeavored to give it a different look, to best utilize the digital technology he had available to him. (Sci-Fi Universe, issue 5, p. 60)
Both the Enterprise-D and Bird-of-Prey were represented with studio models. Though the sequence was therefore primarily handled with motion control, CGI was used for the weaponry and strikes in the battle. (The Making of the Trek Films, p. 168) Photon torpedoes incorporated into the clash were rendered by John Knoll, taking inspiration from photon torpedo effects work in Star Trek: The Motion Picture. Phasers and disruptors in the encounter were done by Don Butler. Although the deflector shields in the sequence retained an oval shape from Star Trek: The Next Generation, considerable thought and experimentation went into how detailing of the shields would look, as the majority of the shots were to be close-ups of the ships in combat and would therefore clearly show the shields in detail. In views of the Bird-of-Prey distantly firing on the Enterprise in the foreground, the Klingon ship initially seemed to subtract from the effect of the Enterprise's shields flaring, so the Bird-of-Prey was changed to look smaller in those shots. (Cinefex, No. 61, p. 74) The impacts were shown using computer-generated and traditional compositing techniques; these included flashes of light – the digital equivalent of a tried-and-tested approach, involving the visual presence of some burning steel wool on supposedly charred areas – and computer-generated debris that was made to look as though it was flying. (The Making of the Trek Films, UK ed., p. 168)
The live-action footage from the battle involved stunts coordinated by Bud Davis. Strikes to the ships were filmed with the commonly used method of having the actors and camera shake. Never having worked on a Star Trek film before, Davis initially doubted that this routine would be effective, though he was convinced otherwise as the movie's production progressed. (audio commentary, Star Trek Generations (2010) DVD/Blu-ray)
Like many of the effect visuals in Generations, virtually all the views of the battle were omitted from the first work edit of the film but were inserted into the movie for its second cut, which was exhibited as a test preview. The first assembly of the film's live-action footage from the sequence also involved not only slightly more footage than in the movie's second work print and the theatrical cut, which were much the same as one another, but also several alternate takes. The cut footage establishing damage to one of the Bird-of-Prey's nacelles was in only the first edit of the film, as was the inconsistent visual effect shot of the ship decloaking. The only visual effects footage found in all three edits of the confrontation were the views of the decisive photon torpedo firstly being fired from the Enterprise and then streaking towards the Bird-of-Prey, as well as the recycled footage of the Klingon ship exploding. (X) Of how the sequence was edited, David Carson stated, "We developed the Klingon battle into this huge, noisy battle." (The Making of the Trek Films, p. 163)
There were shocked reactions, even from members of the production crew, to the revelation that the battle results in the deaths of Lursa and B'Etor. "When we filmed it for the first time," related Barbara March, "everyone on the set started crying out 'No, no, no, you can't kill off the Duras sisters!' Obviously that plot twist was a surprise to a lot of people." (Star Trek: Communicator issue 104, p. 52) Some Star Trek fans were outraged that the fighting ends with the Duras sisters being killed off. In fact, some fans were more dissatisfied with this conclusion to the fray than their unhappiness at Kirk dying. (audio commentary, Star Trek Generations (Special Edition) DVD/Blu-ray) One of these disappointed fans was Manny Coto. In hindsight, he related about the Duras sisters, "I was sorry to see them die, I thought it would have been nice to keep them going." (audio commentary, Star Trek Generations (2010) DVD/Blu-ray) At one stage, Barbara March sympathized with the fans' complaints by lamenting the elimination of her character as well as that of B'Etor, though March also conceded, "I think it was inevitable that we had to die. Villainess sex goddesses must die – that's the truth!" 
Production staffers such as Brannon Braga and Rick Berman were proud of the battle sequence. While editing the movie, Berman commented, "To my delight, the battle and demise of the Klingon vessel is an incredible action-adventure sequence." Berman also cited it as one of several parts of the film that surprised him by how good (in his opinion) they turned out. (Star Trek Generations (novel), hardback ed., p. 278) Brannon Braga once remarked that the skirmish was "cool." He proceeded to state, "I really enjoyed the space battle, and it came at a point in the film when there had been no action since the opening. Maybe a little too long, so finally we get excited. This is good old-fashioned Star Trek." In addition, Braga described the presentment of the Bird-of-Prey's annihilation as "great stuff" and Ronald D. Moore referred to the same finalé as "pretty cool." (audio commentary, Star Trek Generations (Special Edition) DVD/Blu-ray) In agreement, David Carson called the explosion "terrific." Other parts of the battle he cited as highlights include the shot of Riker ordering the detonation, which pans from Worf at the tactical station to Riker, and the two final views of Lursa and B'Etor, utilizing John Alonzo's snap zoom. (audio commentary, Star Trek Generations (2010) DVD/Blu-ray)
Even though Manny Coto was regretful about the demise of the Duras sisters, he highly approved of the battle that precedes it. Coto described the stunt work of "people flying over the bridge" as "very well done," adding, "I don't think I'd ever seen [that] before in a Star Trek movie [....] It's terrific stuff." He also called the shot of the Bird-of-Prey's elimination "a great explosion." (audio commentary, Star Trek Generations (2010) DVD/Blu-ray)