- "I hope my transmitter is strong enough to reach off-planet. Rebel Alliance, this is a transmission from the planet Calamari. We are under assault from massive World Devastators…"
- ―Gammack relays his distress call to Pinnacle Base
During the battle, Captain Gammack ordered evac shuttles to the frontlines to carry out the wounded before the World Devastators could overrun their positions. He also protested the decision to pull back to a location far from the main battle, but was told it was to avoid getting caught in a wedge formation by the Devastators.
After a brief discussion, he was granted time to send a message to the Republic base on the moon of Da Soocha V. His message was only partially sent, as the World Devastators reached his position before he could finish.
When Lando Calrissian's task force reached Dac, Green Leader contacted Gammack, telling him to prepare his troops for evacuation. Gammack expressed his relief and informed the squadron leader that his battalion was the only unit left in the sector of the battle. When the Devastators released the TIE/D automated starfighters, he informed Green Leader of the fighters on his tail, but was unable to prevent his death.
After the battle turned against the New Republic, he attempted to shore up his soldiers' remaining Amphibion attack boats for a boarding attempt of the nearest Devastators. When the ships were affected by the overriding command signal, Gammack's troops boarded the Devastators and fought their way onto their decks, only to be told by the Millennium Falcon to leave the craft as they were about to be destroyed.