First Alliance-PLANT War
Martin DaCosta served as Andrew Waltfeld's second in command on board the Lesseps until it was heavily damaged by the Archangel and Waltfeld was defeated by Kira Yamato's GAT-X105 Strike.
Gundam SEED Astray R
DaCosta appears in the second volume of Gundam SEED Astray R, taking place after the battle in Africa. The Junk Guild team arrives in Africa looking for a ship to use on land after their original spaceship had been damaged and crashed to Earth. They discover the damaged Lesseps and decide to claim it. However, Martin is still on board the Lesseps and at first does not let Lowe and the Junk Guild take it (the manga suggests that he's guarding a medical pod containing the injured Waltfield). Lowe Guele then asks Martin for his permission to help him fix the Lesseps. DaCosta agrees. However, Blue Cosmos is also in the area, and knowing that there is a coordinator aboard the Lesseps, they decide to attack. ZAFT soldiers also attempt to destroy the Lesseps because they were informed that Blue Cosmos is using it now. However, Lowe Guele in the Astray Red Frame is able to defeat all the enemies and ultimately causes the Blue Cosmos forces to retreat. DaCosta is then shocked that Lowe Guele, who is a Natural, would help a Coordinator and fight off Blue Cosmos, who are Naturals like Lowe. This makes DaCosta question the entire war and could be the reason why he joins the Clyne Faction later on in the series. The two develop a strong friendship and part ways.
Three Ships Alliance
Later, Martin DaCosta joins the Clyne Faction and helps move Lacus Clyne underground after the theft of the ZGMF-X10A Freedom. DaCosta then helps rescue Athrun Zala, who has been held prisoner by his father, Patrick Zala, at the request of Lacus. He is successful in rescuing Athrun and the two escape to the Eternal, a new ZAFT support ship stolen by the Clyne Faction, which has his former superior Andy as a captain.
Gundam SEED X Astray
Second Alliance-PLANT War
DaCosta returns to his position on board the Eternal. He also works to gather intelligence for Lacus on Gilbert Durandal, the chairman of PLANT. He manages to find out more about Durandal's "Destiny Plan" while investigating the Mendel Colony, where Durandal once worked as a scientist. His discovery turns out be exactly what Lacus was seeking but he was spotted by a Reconnaissance Type GINN during his escape and ended up leading ZAFT right to the Eternal and Terminal's secret mobile suit manufacturing plant. Fortunately, after the Eternal leads the ZAFT forces away from the factory, Kira Yamato soon arrives in the MBF-02 Strike Rouge, and after receiving the ZGMF-X20A Strike Freedom eventually disables all of the ZAFT forces.
- As with the other ship captains, Martin is not a playable character despite having a cut-in and voiced lines in Mobile Suit Gundam SEED Battle Destiny. He only appears the the EAF story mission "The Burning Sandstorm" and the Another Arc mission "Dog Run". In both instances, he serves as the captain for the Lesseps-class battleship.