Welkin was born in the small town of Bruhl, the son of the First Europan War hero and General Belgen Gunther. He enrolled in a university to study natural science, and while there decided to focus his secondary military education on tanks. After the Second Europan War broke out, he left school to help his adopted sister, Isara, pack up and flee the advancing Empire. The Empire attacked as he was doing so; after fighting through the initial wave, he took command of his father's tank, the Edelweiss, and bought time until the town fell after an artillery bombardment.
Welkin was then conscripted as a Second Lieutenant, and placed in charge of Squad 7 of the Gallian Militia, and was allowed to keep command of his tank. He won the respect of his men by leading successful and inventive campaigns against the Empire. One such battle was in the Barious Desert, where he ran into the Maximilian, Crown Prince of the Empire, and his durable, massive tank, the Batomys. After a long struggle, Squad 7 took the tank out of action.
After several successful operations, Welkin and Squad 7 were sent on a suicide mission to reclaim a strongpoint that guarded the Empire's sea supply lines. Despite the mission's success, his sister lost her life in the battle. With morale at an all-time low, Squad 7 was ordered to retake Bruhl, Welkin's hometown. With that boost in motivation, Welkin was then deployed to Naggiar Plains. After stopping an artillery barrage Squad 7 held off Selvaria Bles, a Valkyria who entered the battlefield after single-handedly destroying a Gallian tank regiment, long enough to complete their objective. Despite Alicia - his Sergeant and love interest - receiving an injury and subsequently awakening as a Valkyria, the operation was a success.
Later, Welkin would lead Squad 7 on another suicide mission to reclaim a border fort that would fully cut Imperial supply lines. They took a frontal assault as a diversion to allow a train filled with explosives to blow a hole in the entrance, and they then funneled in. They took the base with an all-out assault on its defenses, and captured Selvaria Bles; the general sacrificed her life to set off
a nuke her Last Flame, which obliterated the fort. Maximilian took advantage of the situation and unleashed the Marmota, a massive armored vehicle that bulldozed all in its path.
After trying and failing to stop the Marmota with traps, Maximilian takes the Gallian capital and a superweapon hidden within. Welkin and Squad 7 lead an assault to disable the Marmota, succeeding and eventualy vanquishing Maximillian himself, who used technology to replicate the powers of a Valkyria. He retired from the Gallian Militia as the small nation's part in the war came to a close, a decorated war hero and still a Second Lieutenant.