I know there are two Elder Scrolls interest checks already up. I began writing this a week ago, so I guess the Elder Scrolls are just a popular setting for an RP. If anyone has any questions about the plot, feel free to ask. Basically everything mentioned below will play a role in the story.
The years 226-228, of the Fourth Era.
Shortly after the Civil War in Skyrim, the Empire's grip on Tamriel was reduced to Cyrodiil. Though no hostilities were held between the Empire and any of the other Provinces, they claimed independence and were ruled by their own governments.
For years the Empire has been trying to find a way to spread out of Cyrodiil. To do this, they lifted the outlaw on slavery. With the failed attempt to take control of Skyrim, 27 years prior, still fresh in their minds, the Empire looked south. Before they could make a move, the Empire would need to know they would not have to worry about any northern intervention. The Emperor secured a treaty with High Rock, Hammerfell, Skyrim, and Morrowind to ensure this. Though the specifics of the treaty remain unknown, it is known that all four provinces were promised an equal stake in the south. Once the treaty was secured, the Empire made their move. With a combined force, from the five northern provinces, of 23,000 soldiers, the Empire invaded Elsweyr. Invading from north proved easier than initially expected. The Imperial Legion's warpath was almost unstoppable. The northern cities were easily conquerable, and their people were enslaved. Once the Legion started running into the southern jungles and forests, they were slowed considerably. The Mane, ruler of Elsweyr, assembled militias in these jungles and forests to stop the Empire. The guerrilla warfare tactics used by the Khajiit proved to much for the Empire, and they pulled back to the badlands in northern Elsweyr. Once Imperial control in northern Elsweyr was established, they moved east.
Black Marsh proved to be just as difficult as southern Elsweyr. The Argonian denizens of the marshlands were already expecting an invasion, so they took the weeks prior to prepare. The Empire faced many losses at the hands of the Argonian army, and even more at the hands of the King's elite Shadowscale assassins. However the sheer number of Imperial soldiers eventually overwhelmed the Argonians. The Legion eventually pushed to the capital city Helstrom. The siege of Helstrom was a bloody and terrible loss for the Argonians. Spreading out their forces on the border to prepare for the invasion made it impossible to fight back the Legion at the capital. The Argonian King was seized and publicly hung. The following months also proved to be brutal for the Argonians. Thousands of them were brought from Black Marsh and sold around the Imperial provinces. With Elsweyr and Black Marsh under Imperial control, The Empire looked to expand west.
Valenwood and the Summerset Isles were the last target of the Empire. The Thalmor, who now controlled Valenwood and Summerset Isles, would not be conquered by the Empire, but also saw that a war would cost them many lives. The Thalmor instead called for a rewriting of the White-Gold Concordat. The Thalmor still denied to see Talos as a God, but they could no longer hunt down his worshipers in the Empire because it had grown to strong. The new treaty legalized the worship and acknowledgement of Talos (which made the Nords happy). For years the Thalmor banished all non-Bosmeri and non-Thalmor from the lands. The truce would open trade and allow Imperial citizens, and officials, to enter Valenwood. In exchange, the Empire promised that no Bosmer or Altmer would be enslaved or encroached upon by the Empire. With the Emperor agreeing to this, it would seem like the Empire would stop it's rapid expansion.
The year 230, of the Fourth Era.
For two years the Empire has ruled almost all of Tamriel. With the downfall of the Argonian monarchy in Black Marsh and the peace made with the Thalmor, it would seem the only threat to Imperial supremacy that remained was southern Elsweyr. While the Empire was fighting in Black Marsh and making peace in Valenwood, the Khajiit in Elsweyr were planning to liberate the north. Once things had calmed down in the Empire, the Mane (leader of the Khajiit), led his first raid on the Empire. The Battle of Corinthe was the first step in a long campaign against the Empire. Because Corinthe was located on the border of Imperial/Elsweyr territory, many of it's citizens rose up against the Empire. The battle only lasted three days. On the third day the Imperial Emissary was beheaded and his remains were sent to Imperial City. Just weeks after the battle at Corinthe, the Mane led another assault. This time he attacked the city of Orcrest. This battle would last much longer, and result in many more casualties. Orcrest was home to many Orcs, and though the Orcs did not care for the Empire, they disliked Khajiit more. The Orcs and Imperial guard were outnumbered by the Khajiit but managed to hold to city for ten days. On the tenth day three Imperial garrisons arrived to reinforce the city and push back the Khajiit army. For six more days the battle raged. Eventually the Mane decided that the effort was in vain, and pulled back his forces. This was just a tactic though. Two Imperial garrisons returned north shortly after the Khajiit fell back. Once scouts informed the Mane of this, he decided to attack again. This time he caught the city of guard completely. Within two days Orcrest fell to Khajiit control.
With the Khajiit continuing the push north, the Emperor was looking for ways to stop them. It was only a matter of time before the Khajiit pushed to the southern border of Cyrodiil. His solution was to call upon his "allies" to the west of Elsweyr. The Thalmor were apprehensive at first, but eventually decided it would benefit them to help the Empire. Thalmor soldiers were sent in from the west. The Khajiit campaign climaxed at the Battle of Dune. The battle lasted for two weeks and three days. The Khajiit made their move first. They attacked at night thinking they would catch the Empire off guard, but spies had informed the Emperor that this was the Mane's plan. The Emperor was able to reinforce Dune in the days leading up to the assault. The first week and a half was a back and forth battle. Every few days the Khajiit would push into the city and then be pushed out. On the fourteenth day, the Thalmor arrived. Using a combination of might and magic, the Empire crushed the Khajiit army and captured all survivors. The Mane was also captured in this battle. Many thought the Emperor would have him executed, but that was not the case. Instead the Mane, and his officers, were sent to Blackrose Prison in Black Marsh. With the Mane captured and his fight against the Empire having failed, the Empire was able to spread into southern Elsweyr with almost no resistance. They recaptured all Corinthe, crossed the border, and then began capturing cities in the south. Due to bad blood created during the war, many Khajiit in the south were beaten and killed by Imperial soldiers. A hatred for the Empire is still strong to this day. Once the Empire had rooted out and killed all resisting Khajiit in Elsweyr, they were able to start shipping slaves north.
With the Empire now controlling almost all of Tamriel, one would think Titus (Mede III) would cease to try to expand his reach. That would be a false assumption. During his time as Emperor, Titus had heard many legends of far off lands that were ruled by no race of Man. Using history as a guide for his planning, the Emperor came up with an idea on how he would expand further. His next target would be either Pyandonea or Akavir. Both were extremely difficult to reach, and equally dangerous once reached.
The year is 231, of the Fourth Era.
The sun beats down on the deck of a large ship. Hanging above the ship's mast is an Imperial banner. The deck of the ship is almost covered by slaves. They are not solely Argonian or Khajiit slaves, they vary. Some are prisoners of war and some are criminals. Some volunteered themselves to pay of debts, but the rest were just captured and forced into slavery. There are six armored men walking up and down the deck. Each carries a sword in one hand and a whip in the other. Standing near the wheel is the captain. A mean spirited man of about fifty, his age shows. Below deck more slaves and more Imperial soldiers move about. The captain has the slaves work so there is no chance of revolt, no down time. Just two days earlier the ship left port at Senchal, destined for Solitude. All of the slaves were at one point housed at the infamous Blackrose Prison. The ship has one scheduled stop before Skyrim, the city of Anvil. In the distance pieces of the Valenwood jungles can be seen. A heavy mist comes in from the west, making the distant Summerset Isles invisible. The captain continues to look off in the distance. Eventually he yells to his first officer.
"A storm" the captain points to the gathering clouds. "Get them below deck! Do it fast". Imperial soldiers begin cracking their whips and barking out orders. The slaves are quickly ushered below decks. Once under the deck, the soldiers begin chaining their hands together. Because of the urgency, some chains are not completely latched, but no slave mentions it. The slaves sit ten to a row in three rows. They sit on wooden benches with their hands in their laps and their heads facing down. The Imperial soldiers yell out some more orders about being silent, and then go to their quarters. Above deck the storm draws nearer. Lightning cracks in the distance and the roar of thunder can be heard. Clouds begin to gather over the ship. The captain walks to his quarters, drink in hand, and sits down on the bed. Just as he goes to take a drink, the ship begins to shake. Monstrous waves crash against both sides of the ship. Lightning strikes the water near the ship. Eventually the luck runs out and a massive tidal wave capsizes the ship. The slaves whose chains are not fully latched, are tossed from their seats on the benches. Most of the freed slaves manage to break free of the ship and swim to the surface, only to be confronted with the horror of a massive ongoing storm. The waves manage to drown out the consciousness of those who escaped. Those who do not die awake hours later, half naked and exhausted, on the shores of Valenwood.
A timeline from 4E 201 to 4E 231
This timeline has the events that were more detailed but not too important to the plot
4E 201 - The Events of Skyrim unfold. Alduin and the dragons appear in Skyrim. The Dragonborn kills Alduin, many dragons still live. The Imperial Legion and Stormcloaks battle for control of Skyrim, eventually ending in a final battle at Solitude where General Tullius is killed. Contrary to popular belief, the Dragonborn does not interfere in the war. Titus Mede II is assassinated.
4E 205 - Titus Mede III ascends to the throne at the age of 24, and becomes Emperor. Morrowind, High Rock, Hammerfell, Elsweyr, and Black Marsh cut all ties with the Empire, establishing their own governments. The Forebears defeat the Crowns and take complete control of Hammerfell. Morrowind is divided into five sections and each section is given to one of the five Houses. The Mages Guild is rebuilt in High Rock. There they become the ruling faction of High Rock. Elsweyr's leader, the Mane, takes control of his province. A monarchy is established in Black Marsh to rule over the towns and tribes of the province.
4E 209 - The Thalmor dissolve all governments and tribes in Valenwood and the Summerset Isles and take control. The leader of the Thalmor is killed in battle in Valenwood. Wrestemor, a young Altmer from the Summerset Isles takes the reins, he calls himself "King of the Thalmor". Unlike his predecessor, Wrestemor takes a more lax stance on the worship of Talos, though he doesn't lift the outlaw on Talos worship.
4E 210 - Titus Mede III starts expanding the Imperial Navy and Legions. Soldiers are recruited at a younger age, and mandatory training is a requirement of all citizens in Cyrodiil. Thalmor are denied access to Cyrodiil. One of the Emperor's advisers comes up with a plan to enslave the southern provinces.
4E 215 - Titus Mede III addresses his people in Imperial City, he states: "I see a new Empire on the horizon, a stronger Empire, a unified Empire. An Empire that spans coast to coast, mountain range to mountain range, an Empire of Tamriel.". Most assume that he is planning to start invading other provinces because of the expansions to the military.
4E 218 - Most in Tamriel forget about the speech made three years prior by the Emperor. The Thalmor sending soldiers to Valenwood.
4E 223 - The Crowns and Forebears engage in civil war in Hammerfell. Many are killed on both sides.
4E 225 - The Jarl of Whiterun and the Jarl of Markarth have a dispute that leads to a civil war. The other holds manage to stay out of it, but there is still a significant amount of casualties. Nobles are assassinated in both Holds.
4E 226 - Emperor Titus Mede III holds a meeting with the leader of the Forebears. He promises to help fight the Crowns if Hammerfell will join the Empire, they agree. The Emperor sends an emissary to Skyrim to meet with the Jarls from all 9 Holds. The emissary says the Empire will force the Thalmor to lift the ban on Talos worship if Skyrim joins the Empire. The Skyrim Civil War is ended and Skyrim joins the Empire. The Emperor sends an emissary to Morrowind to meet with the leaders of the five Houses. The heads of each House want the same thing, a stake at Black Marsh. They are promised a piece of Black Marsh and join the Empire. The Emperor meets with the Arch-Mage. The Arch-Mage wants to be able to open smaller sects in the other provinces, seeing no problem the Emperor agrees. High Rock joins the Empire.
4E 227 - The Empire sends soldiers into Hammerfell. There they kill the leaders of the Crowns and help install the Forebears as permanent leaders. After this the Empire assembles soldiers from all five provinces and launch an attack on Elsweyr. The Legions fight their way to the edge of the southern jungles but cannot advance, they create a border and cease their attacks. Imperial Legions attack Black Marsh from Cyrodiil and Dunmer soldiers attack from Morrowind. The Legions fight for the remaining months of the year, and in the last month they reach Helstrom.
4E 228 - The new year begins with the Siege of Helstrom. For almost two days the Argonians hold back the Legions, but eventually the city falls. The Argonian King is captured and publicly hung. Once Black Marsh fell, the Thalmor King, Wrestemor, sought an audience with Emperor Titus Mede III. During the meeting the White-Gold Concordat is re-written. Seeing that the Empire has grown to strong to fight, Wrestemor decides to make some concessions. The ban on Talos worship in Tamriel is lifted. Imperial citizens and officials are permitted to enter Valenwood and the Summerset Isles. In return the Empire does not invade and does not enslave any Altmer or Bosmer in Valenwood or the Summerset Isles.
4E 230 - The Mane leads an assault on the Empire in northern Elsweyr. The Battle of Corinthe lasts three days and on the third day, the Imperial Embassy is raided, the Emissary killed, and all Imperial soldiers are run out of the city. Weeks later the Mane attacks Orcrest. The Orcs and Imperials at Orcrest outlast the Khajiit militias for ten days before reinforcements arrive. The battle continues for six days. Eventually the Mane orders a retreat. Days later two Imperial Legions leave and the Khajiit attack again. Within two days they seize control of Orcrest. The Khajiit continue to push north. Titus Mede III calls upon the Thalmor for aid from the west. Knowing that the Empire would eventually be able to crush the Khajiit on their own, the Thalmor King decides to help because he did not want any retaliation from the Empire. The Khajiit attack Dune, resulting in the Battle of Dune. The battle lasts for two weeks and three days. The first week and a half prove to be a slaughter for both sides, the Khajiit look to have the battle. Then the Thalmor arrive. The Thalmor and Empire crush the Khajiit and capture the Mane. The Mane is sent to Blackrose Prison. A Khajiit hatred for the Empire still exists.
4E 231 - Emperor Titus Mede III plans to expand his Empire further, looking east to Akavir and southwest to Pyandonea, though this plan remains a secret to all but him. An Imperial slave ship is capsized off the coast of Valenwood.