(U.C. 0079.12.03 - 0079.12.07) With Zeon losing their foothold on Earth, the 603rd is given a new project — to infiltrate a prototype weapon into the Federation airspace and attack Federation warships launching from Jaburo. Ensign Werner Holbein, an arrogant naval officer who boasts a proud maritime family tradition, is assigned to the Jotunheim to pilot the mobile diver unit Ze'Gok. However, the testing goes well below expectation, as both Holbein's test drop ends in failure after unable to score any hit with the Ze'Gok. On the third and final drop, Holbein manages to destroy a handful of Federation ships with a direct reentry/free descent before letting loose the attached "Kuhblume" beam scatter cannon. Before he could celebrate, two Core Booster II fighters arrived and shot down both the Ze'Gok and the retrieving Gaw carrier, killing Holbein in the process.

(U.C. 0079.12.28 - 0079.12.30) Situation for Zeon is getting desperate after the Federation successfully sieges the space fortress Solomon. Upon arriving at A Baoa Qu, Jotunheim is visited by Col. Herbert von Kuspen, a uptight high-rank commander from an elite battalion, who immediately try to assume command of the ship but meets resistance from both Monique and Prochnow. The ship is then reinforced with "Principality's elite soldiers" — turns out to be a group of young cadets forcefully mobilized from the homeland. To Monique's shock, the most enthusiastic soldier out of the inexperienced recruits is nobody other than her own younger brother Erwin. The Jotunheim is then dispatched to lunar space and ordered to test and perfect the Oggo mobile pods. At Granada airspace they run into a small Federation forces, and Erwin leads a squad of three Oggos to engage in combat.

(U.C. 0079.12.31 - 0080.01.01) Just as Gihren Zabi proudly announces to his troops the decimation of the Federation fleet by the Solar Ray, the 603rd received its latest prototype weapon — the massive Big-Rang mobile armor. When the Federation launches a large-scale desperate attack on A Baoa Qu from two directions, the Kuspen Combat Battalion is assigned to defend the E field, and Oliver (to his shock) is ordered to pilot the Big-Rang. When the Jotunheim encounters a vanguard detachment of the Federation fleet, Oliver manages to inflict heavy casualty on the Federation forces with the help of Monique and Kuspen. Although the Big-Rang pushes back the first wave of attack, vengeful Federation soldiers eventually overwhelms and destroys the mobile armor, as well as killing Kuspen. As the retreating Jotunheim mourns the loss of their friends, a small group of survivor mobile suits approaches, among them an alive Oliver held by Monique's heavily damaged Zudah.