Catalyst Game Labs, the current owners of BattleTech, have divided history into eras and sub-eras. The products they release are grouped in this manner.. To reflect how the 1,000 lightyear separation between the Inner Sphere and the Clans renders Inner Sphere-centric era titles meaningless, Catalyst created a concurrent but disparate Clan Homeworlds Era in 2021.
|Pre-Star League||Pre-Spaceflight||Before 1950||Earliest era referenced - when humanity only resides on its planet of origin, Terra.|
|Early Spaceflight||1950 – 2005||Early spaceflight, restricted to the bounds of Sol. Notable events include the Second Cold War and reestablished Soviet Union.|
|Star League||Age of War||2005 – 2570||The era of the Terran Alliance, the colonization of the Inner Sphere, the formation of the Great Houses, and the Age of War.
KF Drive tech is introduced, beginning the First Terran Exodus in the 22nd century. In 2235 unrest sparks the Outer Reaches Rebellion, the Alliance loses and issues the Demarcation Declaration, setting most colonies free and sparking the Second Terran Exodus. Throughout the 23rd and 24th centuries the first independent interstellar nations are founded throughout the Inner Sphere, and the Periphery is settled.
The Alliance transforms into the more powerful Terran Hegemony and the Great Houses forge their own empires as neo-feudalism becomes dominant. The Age of War begins in 2398 and will last until the mid-26th century.
|Star League||2571 – 2780||The time of the First Star League from its founding in 2571 to the fall of the usurper Amaris Empire in 2780.
For nearly two centuries humanity is united under a single government. Advancements in science and engineering backed by the greatest military in history uphold nearly two centuries of peace and prosperity across all settled worlds. Save for minor conflicts dubbed the Hidden Wars, the SLDF rarely sees true conflict until Periphery revolts break out in 2765.
These rebellions enable Stefan Amaris to destroy the Cameron dynasty and seize the Star League throne for himself, resulting in the Amaris Civil War. Although Aleksandr Kerensky and his SLDF ultimately defeat Amaris, the Hegemony and Star League are irreparably ruined.
|Succession Wars ||Early Succession Wars||2781 – 2900||The collapse of the Star League is followed by two devastating Succession Wars.
Following the Star League's dissolution Kerensky and most of the SLDF leave the Inner Sphere in 2784. Within two years the five Successor States are waging total war (including heavy usage of nuclear weapons), each aiming to restore the Star League with its own dynasty at its head. The resulting First and Second Succession Wars span three generations and result in the loss of billions of lives, hundreds of worlds depopulated, and much scientific knowledge lost.
ComStar emerges from the last surviving ministry of the Star League, and by the end of the era has become a pseudo-religious order. Establishing itself on Terra the outwardly neutral order utilizes its monopoly on interstellar communications to manipulate the ongoing wars for its own agenda.
Beginning in 2866, the Third Succession War reflects the general decay across the Inner Sphere as it is an ongoing state of low-level conflict involving small units and raids rather than large armies and massive offensives.
|Late Succession Wars – LosTech||2901 – 3019||With much of the Star League's knowledge gone, the Third Succession War continues.
Advanced technologies have been become LosTech, and in contrast to the preceding wars the Third Succession War is a constant low-intensity conflict throughout this period. Combat grows more ritualized and medieval amongst 'Mechs, with duels being fought between MechWarriors in an effort to preserve what technology remains.
|Late Succession Wars – Renaissance||3020 – 3049||The Third Succession War ends, House Steiner-Davion becomes the Inner Sphere's most powerful dynasty, and the Helm Memory Core is rediscovered, beginning a techno-industrial renaissance.
The status quo is upended with the marriage of Hanse Davion and Melissa Steiner and the resulting union of the Lyran Commonwealth and the Federated Suns. In the ensuing Fourth Succession War the Capellan Confederation is reduced to a rump state and the Draconis Combine suffers heavy losses.
As a result of his nation's defeats Theodore Kurita reforms the Combine military with ComStar's aid and grants independence to the Free Rasalhague Republic. His efforts ensure that the nascent Federated Commonwealth fails to win a similar victory against the Combine in the War of 3039, though it remains the overwhelmingly dominant state in the Inner Sphere. By 3049 a Fifth Succession War and/or House Steiner-Davion's re-establishment of the Star League seems likely.
The discovery of the Helm Memory Core in 3028, coupled with other scientific efforts, begins a technological renaissance during the next two decades. The Inner Sphere slowly begins climbing back towards Star League-era levels of technology.
|Clan Invasion ||3050 – 3061||Coreward of the Inner Sphere, a new faction strikes from the Deep Periphery in early 3050 and changes the Inner Sphere forever.
With superior weaponry, unique OmniMech designs and Elemental infantry, these “Clans” with their warriors genetically bred for war cut through all opposition. During this Operation REVIVAL the Draconis Combine and Lyran half of the Federated Commonwealth lose many worlds, while the Free Rasalhague Republic is almost subsumed entirely. Eventually these invaders' origins become known: they are the descendants of the Star League-in-Exile returned to reestablish the Star League.
In the climactic Battle of Tukayyid ComStar's military arm wins a victory and a truce which halts the invaders for fifteen years. The Successor States frantically upgrade their armies for the inevitable hostilities while the Clans seethe at the enforced peace. ComStar undergoes reforms aimed at secularizing the organization, but dissident zealots exile themselves and form the fanatical Word of Blake in response.
The next two major conflicts erupt in 3057. Clan Wolf wages the Refusal War against Clan Jade Falcon to prevent a resumption of the invasion. At the same time Operation GUERRERO results in the Free Worlds League and Capellan Confederation reclaiming worlds lost during the Fourth Succession War - and sundering the Federated Commonwealth when Katherine Steiner-Davion orchestrates the secession of the rechristened Lyran Alliance.
The Battle of Coventry in 3058 leads to the Successor States forging the Second Star League, with the express purpose of ending the Clan Invasion. They accomplish this when Operation BULLDOG and Task Force Serpent conclude with the annihilation of Clan Smoke Jaguar. After the reborn SLDF wins the Great Refusal, the other Clans agree to end the invasion permanently.
|Civil War ||3062 – 3067||While the Clan threat is ended, the new Star League does not herald a new era of peace but several wars within the Inner Sphere itself.
Taking advantage of the rift in the former Federated Commonwealth and his own realm's Xin Sheng movement, Chancellor Sun-Tzu Liao continues reclaiming former Capellan worlds. His efforts culminate in the Capellan-St. Ives War which ends with the re-absorption of the St. Ives Compact into the Confederation.
While Katherine Steiner-Davion secures the throne of the Davion-half of her parents' realm, her tyrannical rule and tensions within both states finally erupt in 3062. The five-year FedCom Civil War between Katherine's Loyalists and Victor Steiner-Davion's Allies intent on dethroning her ravages both realms and their militaries before Katherine is finally defeated.
Numerous smaller conflicts are fought around the Inner Sphere during this period, most of them derived from the larger civil war. The Jade Falcons attack the Lyran Alliance again, while the Draconis Combine finds itself mired in border wars with both Clan Ghost Bear and the FedCom's Draconis March.
During these years the Word of Blake seizes Terra from ComStar and expands its power base, as well as building up its military might. Dismissing the fanatics as posing little danger, the rest of the Inner Sphere does not interfere.
|Jihad ||3068 – 3080 ||The time period known as the Jihad refers to a major interstellar war that involved all major factions, mainly consisting of the faction called the Word of Blake attacking capitals and other, important industrial worlds to hamper their enemies' capacity to wage war. They created a "white-out" of the HPG grid that forced regional leaders to take a more active role, then manipulated those leaders to create chaos and warfare that distracted their enemies from the Word's activities. Using "hidden" armies they hit former Chaos March worlds in the vicinity of Terra, which led to the formation of the new state, the Word of Blake Protectorate. The Jihad was not only of the Word of Blake assaulting foreign powers, but also civil conflicts that erupted between states due to the chaos and the actions of the factions.|
|Dark Age ||Republic||3081 – 3130 ||With the Word Of Blake's defeat at the start of this era using coalition forces made possible through unifying efforts of Devlin Stone and David Lear to crush them. The formation of the Republic of the Sphere out of the ashes of the Word of Blake Protectorate created a new buffer state between the various Inner Sphere powers. Additionally the Republic set in motion a plan with the other major factions to decommission BattleMechs and other tools of warfare, downsizing armies and removing any such material from the hands of private individuals.|
|Dark Age||3131 - 3150 ||The time since the collapse of the HPG network caused political chaos in The Republic of the Sphere that led to the militarization of Industrial Mechs and other civilian equipment. Then the steady advancement of the Great Houses and Clans themselves began to take back worlds they ceded to the Republic, as the fragmented and stumbling Republic made an easy target. Finally ending with the ilClan Trial being fought on Terra, days after the broadcasted disbanding of the Republic.|
|ilClan||ilClan||3151 – Present ||The once-invulnerable Republic of the Sphere lies in ruins, torn apart by the Great Houses and the Clans as they wage war against each other on a scale not seen in nearly a century Mercenaries flourish once more, selling their might to the highest bidder. As Fortress Republic collapses, the Clans race toward Terra to claim their long-denied birthright and create a supreme authority that will fulfill the dream of Aleksandr Kerensky and rule the Inner Sphere by any means necessary: the ilClan|
|Clan Homeworlds||Clan Homeworlds||2786 – Present||In 2784 General Aleksandr Kerensky launched Operation Exodus, and led most of the Star League Defense Force out of the Inner Sphere in search of a new world, far away from the strife of the Great Houses. After more than two years and thousands of light years, they arrived at the Pentagon Worlds. Over the next two-and-a-half centuries, internal dissent and civil war led to the creation of a brutal new society—the Clans. And in 3049, they returned to the Inner Sphere with one goal—the complete conquest of the Great Houses.|
- New to Battletech? - BattleTech Eras
- Heretic's Faith (2021 Edition), "BattleTech Eras"
- New to Battletech? - BattleTech Eras - Star League
- New to Battletech? - BattleTech Eras - Succession Wars
- New to Battletech? - BattleTech Eras - Clan Invasion
- New to Battletech? - BattleTech Eras - Civil War
- New to Battletech? - BattleTech Eras - Jihad
- New to Battletech? - BattleTech Eras - Dark Age
- Record Sheets: Clan Invasion, p. 4: "Battletech Eras"
- Blake Ascending: A Jihad Compilation
- Era Digest: Age of War
- Era Report: 2750
- Field Manual: 3085
- Field Manual: 3145
- Field Manual: Crusader Clans
- Field Manual: SLDF
- Field Manual: Updates
- Field Manual: Warden Clans
- First Succession War (Sourcebook)
- Handbook: House Davion
- Handbook: House Kurita
- Handbook: House Liao
- Handbook: House Marik
- Handbook: House Steiner
- Handbook: Major Periphery States
- Historical: Liberation of Terra Volume 1
- Historical: Liberation of Terra Volume 2
- Historical: Operation Klondike
- Second Succession War (Sourcebook)