Iron Squadron was a squadron that utilized a YT-2400 light freighter known as the Sato's Hammer, which occurred two years prior to the Battle of Yavin. Mart Mattin was the leader of this cell, having taken over from his father. During the Age of the Empire, this independent rebel cell's base of operations was at Mykapo. In 2 BBY, the Galactic Empire's imposition of martial law on Mykapo led Iron Squadron to become part of Phoenix Cell.
The Squadron known as Iron, which took its name from the historical Mykapo system planetary defense forces squadron of the same name to confuse Imperial Intelligence, was initially commanded by Mart Mattin's father, who was the brother of Phoenix Cell's Commander Jun Sato. Following his death, his son assumed command of the group. The crew consisted of the female Theelin Gooti Terez, the human male Jonner Jin, and the astromech droid R3-A3. Their base of operations was a YT-2400 light freighter called Sato's Hammer.
A small rebel cell called the Iron Squadron emerged on the planet Mykapo during the Age of the Empire. Initially, the Iron Squadron was under the leadership of Mart Mattin's father, a native of Mykapo. After his passing, Mart took over as the group's leader. The Iron Squadron, operating from their freighter Sato's Hammer, engaged in the harassment of Imperial forces within the system. This group was isolated from other rebel cells, including Commander Jun Sato's Phoenix Squadron. Sato had believed the cell was destroyed after losing contact with his nephew Mart.
In 2 BBY, the Galactic Empire placed Mykapo under martial law, dispatching an advance patrol to the system. Iron Squadron engaged this patrol in battle, resulting in damage to their ship's hyperdrive. Shortly thereafter, the Spectres and the Phoenix Squadron arrived to evacuate rebel sympathizers from Mykapo. Hera Syndulla, the leader of the Spectres, intervened to assist the Iron Squadron. Her VCX-100 light freighter Ghost destroyed several TIE fighters that were attacking the Sato's Hammer. Despite suffering casualties, Mart refused the Spectres' offer of assistance, and his ship destroyed the Imperial Gozanti-class cruiser, which served as the command ship for the Imperial patrol.
Following the skirmish, the Iron Squadron docked with the Ghost. Hera, along with her fellow rebels Ezra Bridger, Sabine Wren, and the astromech droid Chopper, visited the Sato's Hammer and discovered that the ship's hyperdrive and systems had sustained damage. Hera and her companions attempted to warn the Iron Squadron about the impending arrival of Imperial reinforcements and the need to evacuate. However, Mart and his crew refused to leave Mykapo, considering it their home.
After Hera returned to the Ghost, Ezra persuaded her to allow him, Sabine, and Chopper to remain behind longer to reason with the Iron Squadron. Ezra and his rebel allies successfully won over Mart's crew by assisting R3-A3 in repairing the ship's hyperdrive. Despite the hyperdrive repair, Sabine and Chopper's efforts were thwarted when Mart diverted power to the ship's laser cannons and deflector shields. When Admiral Kassius Konstantine arrived with an Arquitens-class command cruiser, two Gozanti cruisers, and additional TIE fighters, Mart expressed his desire to confront the Imperials. However, Gooti and Jonner recognized their inability to defeat the Imperials. Gooti, Jonner, and R3-A3 fled with the Spectres aboard the Phantom II, while Mart remained behind.
Outnumbered and damaged, the Sato's Hammer was no match for Konstantine's forces, and its engines were disabled. Mart managed to transmit a distress call, which was intercepted by the Spectres. Prompted by Commander Sato, Hera, her crew, and Iron Squadron collaborated to rescue Mart. Konstantine attempted to ensnare the rebels by placing a magno-mine on Sato's Hammer. However, Hera thwarted this plan by dispatching Chopper and R3-A3 to disarm the magno-mine. After rescuing Mart and his ship, the rebels reattached the magno-mine to a crate and dropped it onto Konstantine's light cruiser, causing damage to the vessel. Iron Squadron and the Spectres received assistance from Commander Sato, who dispersed Konstantine's forces.
Shortly after Grand Admiral Thrawn arrived on his Imperial Star Destroyer Chimaera, the Iron Squadron and their rebel allies made their escape. Upon witnessing the Chimaera, Mart and his comrades realized that they were seeing a Star Destroyer for the first time. They decided to pool their resources and join Phoenix Squadron. After arriving at Chopper Base on the planet Atollon, Mart embraced his uncle along with his crew Gooti and Jonner.
The debut of Iron Squadron occurred in "Iron Squadron," which was the eighth episode of the third season of the animated series Star Wars Rebels.