Who is Roboute Guilliman? The Ultramarines Primarch explained

Roboute Guilliman, also known as the Avenging Son, is the Primarch of the Ultramarines in Warhammer 40,000, and he's not your average warrior. He was a powerhouse, a warlord and a diplomat who ruled his own empire well before the Emperor found him. What sets him apart from his fellow Primarchs is that he didn't see himself as only a fierce fighter. He was all about building civilizations and creating lasting legacies.

During the Great Crusade he led the largest Space Marine Legion and became a legend. After the chaos of the Horus Heresy, when things looked grim for the Imperium, Guilliman stepped up as Lord Commander. One of his major claims to fame is writing the Codex Astartes, which laid down the law for Space Marine tactics and strategy, and he helped create the modern Imperial military structure. This guy was a game changer, and his lore is fascinating.

Roboute Guilliman, Primarch of the 13th Legion, watches over the 500 worlds of Ultramar

Guilliman is the Primarch of the 13th Legion, the Ultramarines, but he's far more than a war leader. He has the 500 worlds of Ultramar under his watch. It's an impressive region of the Imperium of Man, known for its independence, its productivity, its peace and its self-sufficiency.

When the Primarchs were scattered across the galaxy as infants, most of them ended up on worlds you could only describe as not so great. Luckily for Guilliman, he landed on Macragge, a planet that came through the chaotic Age of Strife mostly unscathed. It was like winning the cosmic lottery.

Konor and Tarasha Euten raised Guilliman into a prodigy on Macragge

Guilliman was adopted by Konor, one of the two consuls ruling over Macragge, and he was raised by Konor's trusted seneschal, Tarasha Euten. With such a solid team behind him, it's no wonder he blossomed into a prodigy, excelling in both brains and brawn.

When he was given command of his own expeditionary force, he set off for the rugged, mountainous region of Illyrium to deal with wild tribesmen who were a real pain for the citizens of Macragge. He shone on the battlefield. Guilliman showed off his tactical genius, swiftly earning the respect of his enemies and then putting an end to the threat for good. That was peak heroism.

Gallan's coup and Konor's death made Guilliman ruler of Macragge

When Guilliman returned to the capital, he discovered a coup in full swing. His adopted father Konor had been overthrown by his co-consul, Gallan. Guilliman and his forces rushed in to lift the siege and made a mad dash to Konor's side for his final moments. With his last breath, Konor revealed Gallan's treachery to Roboute.

Fueled by righteous anger, the young Primarch crushed the rebellion with ruthless efficiency, captured its leaders and served up some serious justice. Now the undisputed ruler of Macragge, he got to work reorganizing the entire social structure. Out went the old noble houses, and in came a true meritocracy. He redistributed lands to the people, making sure everyone got a fair shot. It's like "Robin Hood meets Ned Stark in space," and I think he's amazing.

The Emperor gave Guilliman the Ultramarines, which grew into the largest Legion

For five glorious years, Macragge and the worlds of Ultramar flourished under Guilliman's leadership. When the Emperor of Mankind finally arrived to reunite with his long lost son, he was blown away by what he saw: a thriving world buzzing with interplanetary trade and boasting a top notch military. Clearly impressed, the Emperor handed him command of the Ultramarines Space Marine Legion, which to me is a chef's kiss moment.

During the Great Crusade, the Ultramarines were unstoppable, bringing countless planets under the Imperial banner. With a steady stream of recruits from the worlds of Ultramar, they grew to become the largest Legion of them all. They racked up commendations across the galaxy and earned the respect of other Legions and their Primarchs.

Calth, the Shadow Crusade and the Ruinstorm cut Guilliman off from Terra

From the start of the Horus Heresy, Guilliman and the Ultramarines found themselves knee deep in treachery. First, Horus put them on the sidelines right as the civil war kicked off. Then, to make matters worse, Lorgar and his Word Bearers pulled a fast one at Calth, unleashing chaos by irradiating the planet and wiping out Ultramarines by the thousands.

Things got crazier during the Shadow Crusade, when Lorgar and Angron of the World Eaters blazed a fiery trail through the worlds of Ultramar. A massive spell tore reality apart, leading to Angron's ascension to daemonhood and giving birth to the warp storm known as the Ruinstorm. Suddenly Guilliman and the Ultramarines were cut off from Terra, totally in the dark about the bigger war that was brewing.

Guilliman founded Imperium Secundus with Sanguinius and Lion El'Jonson

It was an intense time, driven by a big misunderstanding: the belief that the Imperium had completely crumbled and that Ultramar was all that was left standing. Guilliman decided to take matters into his own hands and created a brand new faction called Imperium Secundus. He teamed up with Sanguinius of the Blood Angels and Lion El'Jonson of the Dark Angels, and together they formed a triumvirate ready to lead the charge.

Despite the schemes of the traitor Primarchs, including a wild rampage by Konrad Curze right on Macragge, news finally reached the triumvirate that Terra and the Emperor were still holding strong. Sanguinius was the first to make a break for Terra, counting on his brothers to keep the traitor fleets busy so he could reach the Emperor's side.

Once the Ruinstorm finally cleared, Guilliman rallied his forces and set off for Terra with as many Ultramarines as he could round up. They raced through space at a nearly impossible speed, but he was hours too late. The traitors were already defeated and Horus was slain, but at a heavy price. Sanguinius was dead, and the Emperor's physical form was shattered, locked away in the Golden Throne for all eternity. As a Blood Angels superfan, I found it heartbreaking.

Guilliman wrote the Codex Astartes before Fulgrim nearly killed him at Thessala

After the Horus Heresy wrapped up, Guilliman got to work again, reclaiming the galaxy from the traitors. He penned the Codex Astartes, a set of guidelines that transformed the massive Legions into smaller, more manageable Space Marine Chapters. It made sure that no single individual could ever again wield that kind of power.

Things took a dark turn at the Battle of Thessala, where Guilliman faced Fulgrim, who had by then become a Daemon Primarch of Slaanesh. In a brutal clash, Guilliman suffered several mortal wounds. The Ultramarines' Apothecaries swooped in and saved him just in time, placing him in a stasis field where he would remain for the next 10,000 years. Talk about an epic nap.

Belisarius Cawl, Saint Celestine and Yvraine brought Guilliman back to life

As the 41st Millennium plunged into darkness, a trio of unlikely heroes set out on a quest to awaken the sleeping Guilliman: the Adeptus Mechanicus Tech Priest Belisarius Cawl, Saint Celestine of the Sisters of Battle, and Yvraine of the Aeldari Ynnari. They crafted a special suit of power armor that not only healed his wounds but brought the Ultramarines Primarch back to life for the first time in ages.

Waking to a galaxy in absolute chaos, Guilliman jumped into action, embarking on a crusade to reach Terra, much as he had during the Horus Heresy. He faced some serious heavyweights, including the Daemon Primarch Magnus the Red and his Thousand Sons, the greater daemon Kairos Fateweaver, the Red Corsairs' Chaos Space Marines, and Skarbrand, the Bloodthirster of Khorne. He powered through and made it to Terra unscathed, finally standing before the shattered form of his father. What a reunion.

Guilliman became Lord Commander of the Imperium and Imperial Regent

In a cosmic wake up call, the Emperor of Mankind telepathically told Roboute that he was humanity's last hope. So the Primarch stepped up and declared himself Lord Commander of the Imperium and Imperial Regent, taking the reins of the Imperium of Man like a boss.

In the lore as it stood when I wrote this, Guilliman was leading the Indomitus Crusade to reclaim the systems lost during the chaos of the 13th Black Crusade. He had already taken down his brother Mortarion in a series of showdowns known as the Plague Wars, even managing to burn part of the Garden of Nurgle itself by channeling the Emperor's power. His latest adventure was setting off into the Imperium Nihilus, a wild and lawless part of the Imperium cut off from Terra by the Great Rift.

The Horus Heresy and Warhammer 40K novels I recommend for Roboute Guilliman

As an avid lore fanatic, I have some recommended reading for anyone who wants to get deeper into his story, because it's so exciting. Although their focus is on Lorgar and the Word Bearers, the Horus Heresy novels The First Heretic, Know No Fear and Betrayer also feature the Ultramarines and Guilliman in an exciting way. Know No Fear in particular is a must read for anyone curious about how devastating it can be when a cool headed Primarch like Guilliman loses his calm.

The later Horus Heresy books The Unremembered Empire, Pharos and Ruinstorm dive into the events of Imperium Secundus and the tough choices he has to make when he's cut off from Terra. It's a cool isolation period. The Primarchs novel Roboute Guilliman: Lord of Ultramar provides key insights into the beginning of his saga, showing him leading his forces into battle at the height of the Great Crusade.

Lastly, probably one of the more recent 40K entries featuring him is the Dark Imperium trilogy: Dark Imperium, Plague War and Godblight. These novels delve into his battles in Ultramar against his corrupted brother Mortarion. From his rise to becoming the last hope for humanity, through his battles against traitors and daemons, Guilliman's story is a testament to resilience and leadership in the darkest of times.