Walhart is the emperor of Valm, the continent west of Ylisse, uniting the continent by force.

Two years after Gangrel's apparent demise, Walhart has all but completed his conquest of Valm. During this conquest he took over Rosanne, leading Virion and Cherche to flee Valm to seek aid from Ylisse and Ferox. Walhart also attacked and took over Chon'sin, killing the parents of Yen'fay and Say'ri. He took the green Gemstone, Vert, and brought it to Valm Castle. After Say'ri left Chon'sin to oppose Walhart, Yen'fay offered to ally Chon'sin with Valm as long as Walhart did not kill Say'ri. Walhart in turn made Yen'fay one of his generals, impressed by the swordsman's strength after he survived a blow from him.

With all of Valm under his control, Walhart decided it was time to invade the continent of Ylisse, sending a vanguard to Port Ferox to help form a staging ground for the rest of his army. Although the vanguard were strong enough to fight off Feroxi soldiers, they were ultimately destroyed in battle. After realizing that it would be a one-sided slaughter if the rest of the invaders arrived, Robin believed that they would have the highest chance of winning if they were to catch the rest of the invading army off-guard at sea.

With the assistance of Validar, the new king of Plegia, ships were acquired. The combined Ylissean-Feroxi army then caught the Valmese navy off-guard at The Searoad. Upon defeating the naval commander, Ignatius, Robin then turned half of the ships into flaming cannonballs that decimated many of the Valmese ships, before heading on to Valm with the rest of their ships. This forced Walhart to devote more of his efforts to stopping the counterattacking invasion force, putting his invasion plans on hold.

After Chrom and his forces seize Fort Steiger, Walhart attacks from the north while Yen'fay attacks from the south. Faced with a dilemma, Chrom decides to deal with Yen'fay's forces first. Pegasus knight 1 a female Pegasus knight serves Walhart with absolute loyalty and obey all his orders.