The Imperial Legion is the main armed force of the Reman Empire, the Septim Empire, and the Mede Empire of Cyrodiil. It is also a large military organization in The Elder Scrolls universe. Based on the concept of the Roman military, the Imperial Legion similarly proclaims itself to be the most disciplined and effective military force in history, and that it preserves the peace and rule of law in the Empire. In The Elder Scrolls III: Morrowind, the Nerevarine may join the Legion, perform tasks for them, and eventually rise in rank up to the highest one, the "Knight of the Imperial Dragon". While playing heavily into the previous installment of the series, Morrowind's sequel, The Elder Scrolls IV: Oblivion, featured the Legion, yet gave the Hero of Kvatch no opportunity to sign up as a legionnaire. In The Elder Scrolls V: Skyrim, the Dragonborn can join the Legion regardless of who they sided with in "Unbound". The Legion also captured and attempted to behead the Dragonborn upon entering Skyrim, beginning the game, because they believe he/she is affiliated with the Stormcloaks, along with Lokir, Ralof, and Ulfric Stormcloak.
The modern Imperial Legion was born from the great army of Tiber Septim, which he used to conquer Tamriel. The Legion remained the greatest fighting force on Tamriel and possibly on Nirn for over 400 years after the death of Tiber.
Emperor Uriel Septim V used the Legion in his conquest of the island kingdoms between Akavir and Tamriel and for his disastrous invasion of Akavir itself, which completely killed two legions off, including the Emperor himself.
One of the noteworthy events is the Umbriel Invasion. The Flying City of Umbriel, the city that devoured souls in the early Fourth Era, had a course directly for the Imperial City, and as it neared the Heartland, the Imperial Legion, along with the Synod and the College of Whispers, tried to mount several attacks upon the Flying City. The Imperial Mages cast Levitation spells so the Legion could reach Umbriel. Unfortunately, the Umbriel War Machine proved too great a force, and the Legionnaires were killed off before they could breach Umbriel. After the Oblivion Crisis, the fall of the Septim Empire, and the Umbriel Invasion, the Legion was greatly weakened, and the once great fighting force had declined greatly.
Years later, the Aldmeri Dominion attacked the Empire in what is known as the Great War. Unprepared for the vicious Aldmeri assault, the Legion suffered heavy casualties.. However, in the Battle of the Red Ring, the Legion surrounded and destroyed Lord Naarifin's forces stationed in the Imperial City. It was a victory such as had never been seen by men against mer since the times of Tiber Septim himself, and it gave the Empire the bargaining tools necessary to sign the White-Gold Concordat. Thirty years after, part of the Legion would be dispatched to Skyrim to stop the Stormcloak Rebellion and end the Skyrim Civil War.
Intended as the sole militaristic force behind Cyrodiil's seat of power, the Legion operates in conjunction with the Imperial City's police-force, the Imperial Watch. Their headquarters are situated in the Imperial City.
The Legion is the primary fighting force of the Cyrodilic Empire, however cities and towns most often have their own City Guard, and do not rely on the Legion for police duties or law enforcement. An exception to this is the Imperial City, which has an entire legion stationed in it.
New recruits must take the oath binding them to the service of the Emperor and the Legion:
"Upon my honor I do swear undying loyalty to the Emperor...
and unwavering obedience to the officers of his great Empire.
May those above judge me, and those below take me, if I fail in my duty.
Long live the Emperor! Long live the Empire!"
Battle formation and rankingEdit
Assuming that there are only 18 legions in the Imperial Legion and a Legion numbered from around 4,200 to 6,000 troops similar to the Roman Legion, then the Imperial Legion has anywhere from 75,600 to 108,000 troops or more if there are more Legions that are unmentioned.
As of Skyrim, the rank structure is like that of the historical Roman Empire, however, including the potential recruitment of the acclaimed Last Dragonborn, there are at least three other Legates encountered. Historically, a legate commanded a legion. Since Fourth Legion is the only legion in Skyrim, only one legate could have existed. Additionally, the rank of General actually did exist, and it was applied to someone who generally commanded more than one legion.
- Private (Mentioned by Captain Aldis)
- First Legion - involved with the Invasion of Akavir.
- Fourth Legion - commanded by General Tullius, the Fourth Legion fought in the Skyrim Civil War against the Stormcloak Rebellion.
- Fifth Legion
- Seventh Legion - involved with the Invasion of Akavir.
- Eighth Legion - fought during the Great War
- Ninth Legion - involved with the Invasion of Akavir.
- Tenth Legion - involved with the Invasion of Akavir and the Great War. 
- Twelfth Legion - appears in An Elder Scrolls Novel: Lord of Souls.
- Fourteenth Legion - involved with the Invasion of Akavir.
- Seventeenth Legion - involved with the Invasion of Akavir.
- Eighteenth Legion - mentioned nominally in An Elder Scrolls Novel: The Infernal City.
- ↑ Brief History of the Empire, v 3
- ↑ Pocket Guide to the Empire, Third Edition: Eras
- ↑ 3.0 3.1 3.2 3.3 3.4 An Elder Scrolls Novel: The Infernal City
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Events and character dialogue in The Elder Scrolls V: Skyrim
- ↑ 5.0 5.1 5.2 5.3 5.4 The Great War
- ↑ Events and dialogue in The Elder Scrolls IV: Oblivion
- ↑ 7.0 7.1 7.2 7.3 Report: Disaster at Ionith
- ↑ An Elder Scrolls Novel: Lord of Souls.