The Nharwaak were heavily dependent on Corellian Engineering Corporation CR90 corvettes to form the backbone of their capital ship fleet. They also used older starfighters, such as the Y-wing.
Together, scientists from these two species worked together to develop a radical new hyperdrive design that was compact and cost-effective enough to be feasibly incorporated into mass-produced TIE starfighters (as opposed to the prototype TIE Advanced x1 design flown by Darth Vader during the Battle of Yavin). Starfighter hyperdrives had been a thorny problem for engineers since well before the Galactic Civil War. Indeed, before the Clone Wars even Jedi starfighters were typically lacking internal hyperdrives and used a Hyperdrive docking ring for interstellar travel.
As such, the joint Habeen/Nharwaak hyperdrive technology was a critical technological development that would have far-reaching implications for both the Galactic Empire and the opposing force of the Alliance to Restore the Republic.
In supplying customers, whether through fear or loyalty, the Habeen chose to serve the Empire, in the form of Grand Admiral Zaarin. The Nharwaak, on the other hand, perhaps out of idealism, decided to provide the hyperdrive to the Rebellion.
Shortly after the Battle of Hoth, when the Habeen began the transfer of the new technology to Zaarin's forces aboard the Nebulon-B2 frigate Shamus, the Nharwaak attacked the rendezvous using a pair of CR90 corvettes, the Charger 1 and Charger 2, and a number of Y-wings and Z-95 Headhunters. This attack was unsuccessful and the convoy survived, in part due to the piloting skills of future Emperor's Hand, Maarek Stele, who would play an important part in thwarting the further aims of the Nharwaak.
The Imperial retaliation was swift. With the discovery of a secret Nharwaak base hidden among a cache of Xizor cargo container lightly defended by Y-wings, Admiral Zaarin was able to mount a TIE/sa bomber attack from the Modified Frigate Shamus. The destruction of the workshop was a setback that severely crippled the Nharwaak scientists' ability to conduct research and development. The attack also destroyed a number of CR90 corvettes, Petor group and Shotgun group, that were carrying missiles and torpedoes, further denting the Nharwaak's offensive capabilities.
Following the destruction of the hidden base, the Nharwaak set about retaliating by annihilating a Habeen tech center near Mylok IV. Unable to send the Shamus in time, Zaarin dispatched the Assassin-class corvette Phoenix with TIE Bombers and TIE Interceptors to defend the Habeen installation. Although intent on inflicting heavy damage, the Nharwaak were eventually driven off by the heroic efforts of Maarek Stele, while the Habeen work crew and station supplies were successfully evacuated.
When the Habeen decided to normalize diplomatic relations with the Empire, the Nharwaak tried to sabotage Zaarin's negotiations aboard the Shamus by sending Y-wings and the corvettes of Phazer group to attack the Habeen Nebulon-B frigate Lendova. Again, Maarek Stele's genius in a TIE Interceptor saved the day by almost single-handedly turning back the Nharwaak fighters. The diplomatic meeting was a complete success, and the Habeen agreed to turn over the new hyperdrive technology to the Empire.
In response to the Habeen's deal, the Nharwaak initiated a deal with the Rebels to turn over the same technology. A meeting was arranged between the trio of Nharwaak CR90 corvettes, Glazer, Coffey, and Janson, and the Rebel Nebulon-B Frigate Xerxes. Zaarin cunningly allowed this meeting to begin, before interrupting it with a deadly ambush of Assault Gunboats and TIE Bombers from the Shamus. The Rebel frigate was obliterated, and with it, the Nharwaak's hopes of aiding the Rebellion.