Background & History
The Demon Tribe's War
Ghirahim's Forces were originally the army of monsters and demons lead by the Demon King, Demise who sought to obtain the Triforce, a divine artifact left behind by the Golden Goddesses. Under the Demon King, they plunged the land in darkness and bloodshed. They where opposed by the Goddess Hylia who protected the Triforce from evil. Hylia gathered the surviving Hylians and used her divine power to raise several land masses up into The Sky, with the largest becoming the land of Skyloft, while she herself remained on The Surface to fight the Demon King and his army, supported by the Gorons, Ancient Robots, Mogma, Kikwi, and Parella that remained on the Surface. Eventually, Demise was defeated and sealed within the Sealed Grounds by Hylia. The remnants of Demise's army rallied under the leadership of Demon Lord Ghirahim, the demonic spirit of Demise's Sword. Under Ghirahim's leadership, it sought to free the Demon King. Meanwhile, their archenemy Hylia created the Goddess Sword and its spirit Fi, before giving up her divinity to be reborn as a Hylian on Skyloft.
Hylia would be reborn as a Hylian girl named Zelda, the daughter of Headmaster Gaepora of the Knight Academy and best friend of a promising young academy student named Link. Unaware of her connection to the Goddess, Zelda would pulled down to the Surface by a cyclone created by Ghirahim while she was flying with Link after the Wing Ceremony. Ghirahim's Forces would have captured Zelda, were it not for the intervention of the Sheikah Impa, who Hylia had entrusted to protect her reincarnation. Meanwhile, Fi would reveal to Link that he was the Goddess' chosen, Hero and her master, destined to wield the Goddess Sword. At the behest of Gaepora and Fi, Link descended to the Surface to find his lost friend and discover his destiny. From Impa, Zelda learned of her destiny as the Spirit Maiden and under Impa's protection journey to the Skyview and Eldin Springs to purify her spirit, while being hunted by Ghirahim and his forces. However due Impa, Link, Fi's interference Ghirahim and his forces were unable to capture Zelda and together with Impa, Zelda managed to flee through the Gate of Time to the past. Ghirahim and his forces would continue to hound Link during his quest to find the Sacred Flames and prevented The Imprisoned Demon King from escaping its seal. Eventually, Link uses the power of the Triforce to destroy The Imprisoned by crushing it with the Statue of the Goddess. However Ghirahim manages to kidnap Zelda and reveals he plans to use her to revive his master in the past. Ghirahim succeeds in reviving his master and transforms back into Demise's Sword. However Link defeats Demise using the Master Sword forged from the Goddess Sword. Defeated, Demise places a curse on Link and Zelda, vowing that his hatred and the curse of the Demon tribe will be reborn in a cycle without end as it evolves, cursing those with the bloodline of the goddess (Zelda and the Royal Family of Hyrule) and the spirit of the hero (Link and his various incarnations). After Demise's body dissolves, his residual consciousness is absorbed into the Master Sword before the weapon is sealed away so the fiend can completely dissolve over time. Demise and Ghirahim's defeat sparks the end of Ghirahim's Forces. However Demise's hatred and the Demon Tribe's curse would continue to plague the land for centuries to come through the King of Evil, Ganondorf.
War Across the Ages
As a result of Cia's use of the Triforce to warp time and space, in order to free the King of Evil's Spirit Fragment sealed inside the Sealed Grounds in that Era. This causes the Gate of Time inside the Temple to be transformed into a Gate of Souls which summons countless monsters into the Era of Skyloft.
The Demon Lord's Plan
Sensing the changes going on in her timeline, Fi descends to Sealed Grounds to stop Ghirahim and his forces from freeing The Imprisoned. In addition to Fi, Ghirahim's Forces are confronted by a Hylian girl named Linkle and her army of Cuccos, who come to Fi's aid. Ghirahim's ritual to revive his master failed, resulting in reviving only smaller fragments of The Imprisoned. Undeterred Ghirahim ordered his Moblin Ceremonial Troops to use the Gate of Souls to increase the rituals power, however they only managed to summon more miniature Imprisoned. Taking advantage of these Mini-Imprisoned, Ghirahim used his Stalmaster Controller Troops to lead the Mini-Imprisoned to attack the Linkle's Forces base. However Linkle and Fi manage to defeat both the Ceremonial and Controller Troops, forcing Ghirahim to use the magic of the remaining Mini-Imprisoned to power himself up. Eventually, Fi and Linkle's Forces manage to defeat Ghirahim and the Mini-Imprisoned. However Ghirahim manages to prevent them from discovering the Gate of Souls, which he eventually uses to revive The Imprisoned.
Cia's Tale: The Demon Lord
After successfully reviving The Imprisoned, Ghirahim uses him to launch an attack on Skyloft. Cia and her Dark Forces appear in the Era of Skyloft, deceiving Fi and the Knights of Skyloft into believing they are allies by defeating Ghirahim and The Imprisoned. During his first encounter with Cia, Ghirahim becomes confused as he senses his master's power within Cia despite The Imprisoned being with him on Skyloft. Upon being defeated, Ghirahim realizes Cia planned to betray the Knights of Skyloft from the beginning and impressed by her underhandedness, joins forces with her. Together with the Dark Forces, Ghirahim's Forces manage to defeat Fi and the Knights of Skyloft.
Land in the Sky
Despite losing the battle, Fi decides to await for the legendary hero to appear. Eventually, Link and Proxi find themselves in the Era of Skyloft and come to the aid of the Knights of Skyloft who are struggling against the combined might of the Dark Forces lead by Volga and Ghirahim's Forces lead by Ghirahim himself. Awakened by Link's presence, Fi offers to assist him despite knowing he is not her true master (the Link of the Era of Skyloft). Working together they manage to summon Levias who helps them be creating bridges to the area of Skyloft controlled by Volga and Ghirahim's Forces. Ghirahim is defeated by Link while trying to attack the Knight Academy Keep, forcing him to retreat, leaving Link and Fi to Volga. Volga proves too strong, forcing Fi and Link to seek the aid of the Great Fairy in powering up Levias enough to weaken Volga, allowing Link to defeat the Dragon Knight. However Ghirahim despite this setback, Ghirahim uses it as an opportunity to brainwash several soldiers in order to destroy the Hyrulean Forces and their allies from within.
Returning to the Sealed Grounds to defend the Gate of Souls from Link and Fi, Ghirahim sets his plan in motion, ordering the Turncoat Leader and his army of Turncoat Soldiers to attack and destroy the Hyrulean Forces from within, to demoralize them. However Link and Fi manage to discover the Turncoat Leader and defeat him. Furious over his minions failure, Ghirahim uses the Gate of Souls to summon The Imprisoned once more. However, Link and Fi manage to use the Groosenator to weaken The Imprisoned and eventually manage to defeat them. With little options, Ghirahim opens the doors of the Sealed Temple and decides to engage his nemeses himself. However he is defeated and knocked into the Gate of Souls by Link. Fi then instructs Link to use the Skyward Strike to close the Gate of Souls, effectively turning it back into the Gate of Time.
Ghirahim would later be resurrected in present day Hyrule by Ganondorf to serve as a general in Ganondorf's Forces and would succeed in aiding Ganondorf in acquiring the complete Triforce. Ghirahim would eventually be defeated by the Hyrulean Forces in Enduring Resolve.