The Sixth Battle of Iserlohn turns into a battle of attrition. Yang Wen-li feels that the Alliance forces should have retreated by this point. His concerns however are not shared by the Alliance commanders, who still adopt a wait-and-see attitude. Meanwhile, Reinhard von Müsel, frustrated at the deadlocked front lines, submits a plan about dealing a fatal blow to the Alliance forces to Gregor von Mückenberger. Mückenberger, while annoyed at Reinhard for jumping the chain of command, has to admit that the plan is good and orders Reinhard to carry out his own plan. By 10 December 794 UC, under Dwight Greenhill's meticulous organisation, the Alliance forces are in a position to withdraw with their main fleet largely intact. At this moment however, Reinhard's squadron suddenly appears in the front lines and begins harassing the Alliance forces. Infuriated at this sudden attack, the Alliance front line commanders begin leading their ships to chase Reinhard, and end up exposing their ships to the Thor Hammer. The Alliance forces thus suffer a major debacle and the Sixth Battle of Iserlohn ends with a decisive Imperial victory.
Prequel to the original series, focusing on Reinhard and his steps up the chain of command in the Galactic Empire. Also focusing on the FPA's Yang Wen-li. A chronicle on how he earned the title "The Hero of El Facile" and his handling of assignments he received after the historic event. Spiral Labyrinth also continues with the background of Reinhard and Kircheis where the first Gaiden left off.
