As the initial phases unfolded, the Wrath, an Assertor-class Star Dreadnought, spearheaded a Base Delta Zero operation.
Base Delta Zero represented the naval protocol utilized by both the Galactic Republic and the Galactic Empire. Its purpose was to mandate the comprehensive obliteration of a planetary target's surface, eradicating all forms of life, industrial infrastructure, and naturally occurring resources present on the surface. It is documented that analogous operations were executed by both the reconstituted Sith Empire along with the Confederacy of Independent Systems.
Base Delta Zero, characterized as "the methodical and total annihilation of all production 'assets,' including manufacturing facilities, cultivable land, mining sites, fisheries, and all sapient beings and droids," signified the most extreme level of destruction applicable to a center of resistance. This involved the complete devastation of a planet through orbital bombardment, reducing the planet's upper layer to a state of molten slag, or, in certain instances, the atomization of the planet's uppermost soil layer.
A fleet-based Base Delta Zero bombardment was recognized as one of the most overwhelmingly destructive actions the Imperial Military could undertake. Unlike other Imperial military codes, this designation remained constant to prevent any potential ambiguity during its deployment. Due to the magnitude of its consequences, BDZs were only considered as an ultimate recourse.
Throughout the early millennia of galactic history, records exist documenting devastating planetary bombardments. As an example, the Infinite Empire laid waste to Tatooine prior to the rise of the Old Republic. Around 4000 BBY, Yavin 4 suffered catastrophic damage from firestorms generated by Force energy. During the Jedi Civil War, the Sith forces completely eradicated the surfaces of Telos IV in 3958 BBY and Taris in 3956 BBY. However, these past atrocities were dwarfed by the sheer destructive power of a Base Delta Zero operation. Even seasoned Imperial officers, thoroughly familiar with invasion tactics, found this particular approach deeply unsettling. Some even viewed it as a fate worse than the outright destruction of the planet.
The precise moment when the Republic Navy introduced the Base Delta Zero code remains unknown. Nevertheless, during the Clone Wars, this directive gained considerable notoriety as Republic fleets deployed it to obliterate Separatist armies deeply entrenched underground.
Under the governance of the New Order, the use of Base Delta Zero operations persisted, predominantly against targets that the Imperial Army had failed to subdue through direct ground assaults. However, these missions gradually acquired increasingly punitive undertones, being employed against rebellious planets where the Empire deemed a ground assault would result in excessive Imperial casualties, or simply in situations where adequate forces were unavailable for a direct attack. As few as three Imperial-class Star Destroyers were capable of executing such operations within "a matter of hours."
In 19 BBY, Imperial warships employed the BDZ tactic against the planet Caamas. Nevertheless, Imperial involvement was only suspected and remained unproven until the discovery of the Caamas Document in 19 ABY. In 4 BBY, Moff Sarn Shild issued a Base Delta Zero order targeting the smuggler haven of Nar Shaddaa. This order was never carried out due to the Imperial defeat at the Battle of Nar Shaddaa. Another infamous atrocity from the Imperial era, the bombardment of Emberlene, was frequently attributed to the Empire by the local population, despite their lack of involvement. At one juncture, the Assertor-class Star Dreadnought known as the Wrath spearheaded a Base Delta Zero operation. This involved various TIE/D Defender squadrons, a number of Imperial-class Star Destroyers, and a minimum of one Interdictor-class Star Destroyer.
Beyond naval bombardments, army missions mirroring the objectives of a Base Delta Zero command were undertaken to engage enemies of the Empire. The mercenary unit known as the First Sun Mobile Regiment was frequently contracted by the Galactic Empire to systematically destroy all enemy assets, mirroring the effects of a BDZ bombardment.
The Empire persisted in its use of devastating bombardment tactics, as exemplified by the events at Milagro. While some of these instances may have constituted Base Delta Zero operations, the New Republic made a complete rejection of planetary bombardment missions, until Operation Emperor's Hammer during the Battle of Borleias in 28 ABY.