That day, the Aldmeri Dominion declared war on the Empire, and I knew that day truly was the begining of the end—Esbern, The Elder Scrolls V: Skyrim
The Fourth Era is an age in Tamriel, the continent where the Elder Scrolls games take place. The Fourth Era starts with the death of the last emperor and heir to the Septim bloodline, Martin Septim. This era is only shown to the player in the events of The Elder Scrolls V: Skyrim.
4E 0 — End of the Oblivion Crisis.
- The banishing of Mehrunes Dagon from Tamriel by the Hero of Kvatch, Martin Septim, and the avatar of Akatosh ends the Oblivion Crisis. The Septim bloodline ends and the Amulet of Kings is destroyed. The Third Era ends, marking the beginning of the Fourth.
- The Fourth Era begins with no Emperor on the throne of Tamriel. High Chancellor Ocato, the Elder Council, and the Blades try to maintain order. The provinces start to take advantage of the Empire's weakened state.
- After the destruction of the Crystal Tower during the Oblivion Crisis, the Thalmor begin to rise to political power, having claimed credit for driving back the Daedra. They begin to purge opposition from government.
- In Vivec's absence, the Ministry of Truth becomes unstable. Vuhon creates an Ingenium that uses souls to stabilize itself. In an effort to free one of the captives used to power it, the Ingenium is destroyed and the rock crashes into the city of Vivec with all the energy it originally had. The impact causes Red Mountain to erupt and destroys the entire island of Vvardenfell, as well as causing massive destruction to the rest of the province.
- Some claim it was incited by the Thalmor,  but it is more likely the result of retribution for the Dunmers' enslavement of many Argonians.
- The Stormcrown Interregnum ensues, fracturing the Elder Council and leading to civil war as pretenders attempt to claim the Ruby Throne.
- Taking advantage of Imperial confusion stemming from the Stormcrown Interregnum, the Thalmor overthrow the existing Altmer monarchy, purging non-Altmer as well as dissidents.
4E c. 22-29 — Titus Mede is crowned Emperor after taking the Imperial City.. This source tells us that Titus Mede ends the Stormcrown Interregnum after 7 years. It is likely, however, that he was crowned before 4E 29, as the Thalmor would have needed time to engineer a coup in Valenwood, which likely required knowledge of the Emperor.
- Seven years after the assassination of Potentate Ocato, the Colovian warlord Titus Mede takes the Imperial City by force with only 1,000 men, becoming the new Emperor.
- The union came about after a Thalmor-backed coup overthrew Valenwood's government. The Empire and its Bosmeri allies are caught off-guard and defeated by Altmer forces that invaded Valenwood supported by Bosmeri soldiers following the coup.
- The city of Lilmoth, Black Marsh, the home of Annaïg, is destroyed in the process.
- The Khajiit credit the Thalmor as their saviors and Imperial influence in Elsweyr begins to wane dramatically.
4E 168 — Emperor Titus Mede II ascends to the throne.
- The Empire is now a shadow of its former glory. Valenwood and Elsweyr had been ceded to the Thalmor, Black Marsh had been lost to Imperial rule since the Oblivion Crisis, Morrowind had yet to fully recover from the eruption of Red Mountain, and Hammerfell was plagued by infighting between the Crown and Forbear factions. Only High Rock, Cyrodiil, and Skyrim remained prosperous and peaceful.
- The Aldmeri Dominion's invasion force overwhelms Imperial defenses.
- After Titus II rejects an ultimatum to make massive concessions to the Thalmor, Aldmeri armies invade. An army led by Thalmor general Lord Naarifin emerges from hidden camps in northern Elsweyr and assaults southern Cyrodiil, flanking Imperial defenses along the Valenwood border. Leyawiin falls to the invaders, and Bravil is surrounded and besieged. Simultaneously, an army under Lord Arannelya crosses western Cyrodiil, bypassing Anvil and Kvatch and entering Hammerfell. This army is joined by smaller forces landing on Hammerfell's coast. Imperial troops are forced into retreat across the Alik'r Desert.
4E 174 — The Imperial City is sacked by Aldmeri forces.
- Titus II flees north from the city, smashing through the surrounding Aldmeri forces with his main army and linking up with reinforcements heading south from Skyrim under General Jonna. The Imperial City falls to the invaders. The Imperial Palace is burned, White-Gold Tower is looted, and the Aldmeri commit many atrocities against the defenseless populace.
- The Reachmen manage to overthrow the Nords in the Reach and take control of the Hold, due to the Legion garrison being called back to Cyrodiil.
- A combined Cyrodillan-Skyrim army led by Titus II is assembled at Bruma. The army then assaults the Imperial City.
- The Imperial City is retaken and Titus II's decision to withdraw from it the previous year is vindicated. Despite this resounding victory, however, the Empire is exhausted and unable to continue the war. Realizing this, Titus II seeks to negotiate with the Aldmeri Dominion to end the war.
- The Concordat is a peace treaty between the Empire and the Aldmeri Dominion. The terms of treaty gave the Thalmor free reign to stamp out the worship of Talos throughout the Empire, and ceded a large section of southern Hammerfell. Critics note that these terms are almost identical to the ultimatum that Titus II rejected at the start of the war. 
- Titus II renounces Hammerfell as a province of the Empire to preserve the treaty after the Redguards oppose ceding their lands. The Redguards see this as a betrayal, and a lasting bitterness between Hammerfell and the Empire is sown to the delight of the Thalmor. Hammerfell continues to war with the Aldmeri Dominion for the next five years.
- Having been fought to a standstill by the Redguards, the Aldmeri Dominion completely withdraws from Hammerfell. The Aldmeri Dominion lost nearly a third of its invasion force during the process. The Imperial lands are left in further ruin and there is political instability. The Aldmeri Dominion further overpower the Imperium in terms of military and economy.
- The Great Reconstruction begins in Cyrodiil, Hammerfell, Valenwood, and Morrowind.
- Ulfric kills the High King Torygg (probably with the help of the Thu'um, although there are arguments for and against this) and proclaims right to the throne, following ancient Nordic custom.  
4E 201 — The Nords of Skyrim engage in a Civil War.
- Ulfric begins the Stormcloak rebellion in an attempt to take the throne of the High King and secede from the Empire.
- Ulfric is captured and sent to Helgen to be executed along with other rebels and two unrelated prisoners after a surprise ambush led by Imperial General Tullius.
- Ulfric Stormcloak escapes the execution, and resumes the position of the Jarl of Windhelm.
4E 201 --- The Dragon Crisis Begins
- Before Ulfric was to be executed, the first dragon seen in centuries attacks and destroys the small keep of Helgen, killing mostly everyone defending the keep outside, but leaving a small number of survivors in the inside: Imperial soldiers, Stormcloaks and an unknown prisoner. 
- The Last Dragonborn is found.