Lord Siglud, the son of Lord Vylon, a descendant of Baldo, one of the 12 Jugdral Crusaders, is a prince of Chalphy Castle of the Kingdom of Grandbell, the center country in the continent of Jugdral. According to unofficial manga, he was born in the Grandbell Calendar Year 734; he stands 178 centimeters tall, and he weighs 70.2 kilograms. He initially wields the Steel Sword, then mostly the Silver Sword (given by Alvis on behalf of Prince Kurth in the Prologue chapter), and later the Tyrfing, which he used in Chapter 5 of Fire Emblem: Seisen no Keifu. Ethlin is his younger sister. Cuan is his brother-in-law and best friend, and Ethlin's husband. His son Celice takes over in Chapter 6 of the game, finishing what he started. According to the end of Chapter 6, Siglud was well loved by many people of the Jugdral continent. Oifey calls him a "kindhearted man" when he rescued Shanan at Genoa Castle in Chapter 1. Mananan, the father of Prince Shanan of the Kingdom of Isaac, often looked to Siglud's father Byron for advice. Since Chapter 3, Siglud was accused of treason against Grandbell by his own country.
Before the onset of Fire Emblem: Seisen no Keifu, Siglud attended the Royal Academy of Barhara alongside his brother-in-law Cuan and Nodion's King Eltshan. Cuan later married Siglud's sister Ethlin. In the Prologue, Siglud heard the news that most of Grandbell's army, including most of Chalphy's army, is en route to invade the Kingdom of Isaac, the northeasternmost country in Jugdral. He also heard that his childhood friend Adean is captured by Gandolf. He was prepared to fight the Verdanian army by himself, but Noish and Alec spoke against it, fearing to let him die fighting alone in the battlefield. Arden joined in shortly thereafter. Finally, the 14-year-old Oifey joined Siglud to be his tactician. Meanwhile, Cuan, Ethlin, and Fin of Lenster heard about Siglud's skirmish with Verdane. They traveled to Chalphy and joined Siglud's cause while Siglud was en route to Jungby. Earlier, Azel joined Siglud's cause without his paternal halfbrother Alvis's consent and invited Lex to join. Siglud fought Dimaggio and conquered Jungby. He begged Midale to rest, but Midale was determined to rescue Adean, thus joining Siglud's cause. Alvis walks over to Jungby territory to assess the state of the conflict with Verdane. Azmur ordered him to give Siglud the Silver Sword. Siglud is regarded by his citizens as a "kindhearted man", and Azel wishes that Alvis could be more like him. Siglud and his army fight off Gerrard's army and conquer Evans castle.
After Siglud conquered Evans castle, Filat dubbed him "Holy Knight of Grandbell". However, Siglud searched all through Evans castle, but no trace of Adean could be found. Henceforth, he traveled deep into the Verdane, the southwesternmost country of Jugdral. He meets with Eltshan at Evans castle. Meanwhile, Dew snuck around Marpha castle and helped Adean escape the clutches of Gandolf with the help of Jamka. Adean went to speak with Siglud and Midale. Then Siglud and his army faced the Genoa army and saved Shanan from the clutches of Kinbois. Shanan told Siglud that he was the prince of Isaac and that his paternal aunt Ira was hostile toward Siglud and his forces already in his army, since she was from Isaac and most of Siglud's army including himself was from Grandbell. Siglud does not care too much about the Isaacian-Grandbellian war, nor does he care what country Shanan is from. Then they marched to Marpha, and Midale took revenge against Gandolf. After the battle of Marpha, Siglud sees Diadora for the first time, but Diadora leaves without telling him her name. Jamka reluctantly goes with Sandima's army and attacks Siglud. Adean tells Jamka that Siglud did not come to Verdane to invade Verdane. Between the thickets of the spirit forest, Siglud sees Deirdre once again, and she joins his cause and would use the Silence staff to prevent Sandima from using the Fenrir tome. After Siglud liberates Verdane from Sandima's control, the dying king Bator tells him about the Loput sect, the organization behind the evil lurking across Jugdral.
When he learned that his friend Eltshan was being held prisoner by his own King Chagall, Siglud opted to rescue him along with Eltshan's sister Rackesis. He was also joined by a bard named Levn (who was in fact the Prince of Silesia, as informed by the Pegasus Knight Ferry, who joined later), a dancer named Sylvia and two mercenaries, Holyn and Beowolf, taking control of Agustria on the way. He worked to restore peace for months, during which Diadora gave birth to his son Celice. But Chagall later attempted to attack again. Siglud intercepted, later hearing bad news from Father Claud about his family being blamed for the death of Prince Kurth, as well as having to nearly fight Eltoshan to the death before learning of his death via execution by Chagall; after that Diadora soon went missing. Afterwards, he rescued Briggid from the Orgahill Pirates as well as rendezvousing with Claud while assisting the young princess of Freege, Tailto. However, Siglud soon found himself surrounded by the Empire's army. He fled to Silesia and was caught in the civil war, ending it and gained the trust of Silesia.
On his way back to Grandbell, he met his father, Byron, in his dying breath. He gave Siglud the Tyrfing, then broken. Repairing it as quickly as he could, he sprung back into action and defeated Langobalt (Lex's father). He sent Oifey and Shanan away with Celice, worried about their safety. While crossing the Yied Desert, Siglud was attacked by the Thracian Dragon Knights. It was after conquering the next castle that Siglud learned that the Dragon Knights, led by Trabant, had ambushed and killed Cuan and Ethlin. On his way to Velthomer, he faced Reptor (Tailto's father). However, during the course of the battle Alvis turned his back on Reptor and cooperated with Siglud to destroy Reptor under the command of Aida. Siglud, however, was unaware to know that it was his turn to be destroyed next.
"I hereby sentence you to death for your acts of treason. No visits to the king today, Siglud." — Alvis to Siglud, during the prelude to the Battle of Barhara.
After he conquered Velthomer castle, Siglud and his army were guided by Aida towards the Grandbell Capital, Barhara for a celebration in their honor. Alvis and his mage unit greeted the battle worn army before Barhara Castle only to quickly turn on them. Siglud was taunted repeatedly by Alvis shortly before Alvis revealed his new wife to be the missing Diadora. After a sad, brief reunion with Diadora(Who lost most of her memory of Siglud, remembering him by only a little), he was executed by Emperor Alvis, using Fala Flame, despite how Alvis was ultimately being manipulated by Manfroy. As time passed, the man formerly known as a traitor to his homeland was later revered as a legendary hero. 17 or 18 years later, his death was avenged by his son Celice.