This is a future history created by the science fiction author Jerry Pournelle. Works have been published by Pournelle and/or collaborators that range from the late 21st to the 31st Century.
The CoDominium is an alliance between the United States and a re-established Soviet Union which imposed world peace. An interstellar drive is discovered which allowed colonies to be established by the CoDominium on planets around other stars. The time period of the CoDominium is from about 2010 to its collapse in 2103. Pournelle published four novels set in this period:
"Prince of Mercenaries"
"Go Tell the Spartans"
"Prince of Sparta"
The latter two books were co-authored with S. M. Stirling.
"Prince of Sparta" ends with the beginning of the formation of the First Empire ruled from the planet Sparta. The period from 2100 until about 2250 is known as the Formation Wars. It ends with the proclamation of Leonidas I of the planet Sparta as Emperor of The Empire of Man which contained all human settled planets.
The First Empire was mostly peaceful until the Secession Wars began around 2600. The Secessionists were led by the planet Sauron which chaffed under Empire rule. They conducted secret bio-research leading to the creation of the genetically enhanced Sauron Super-soldiers. These soldiers had greatly enhanced strength, endurance and reflexes which allowed the outnumbered Sauron coalition fight the Empire at near equal level. Sauron was eventually defeated and the planet devastated by 2640.
This was a Pyrrhic victory since the First Empire collapsed into as set of warring factions. Various claimants to the throne and break-away factions continued until the formation of the Second Empire around 2900.
Haven, a planet at the edge of the CoDominium and the First Empire was used by both as a dumping ground for both criminals and political prisoners. During the Secession Wars, this planet became isolated. This allowed an Sauron warship, escaping the defeat and destruction of the planet Sauron in 2640, to attack and conquer Haven.
"Blood Feuds: A Novel of War World"
"Blood Vengeance: A Novel of War World"
are set 300 years after the conquest of Haven by the Saurons.
In addition, four short story collections were published:
"War World, Volume I: The Burning Eye"
"War World, Volume II: Death's Head Rebellion"
"War World, Volume III: Sauron Dominion"
"War World, Volume IV: Invasion"
dealing with Haven's history from shortly before the Secession Wars to the Sauron invasion and conquest and its aftermath.
A number of these short stories were re-written and incorporated into the first two-thirds of "Blood Feuds". This includes Turtledove's "The Field of Double Sowing" (Vol II) and "Juchi the Accursed" (Vol III). Turtledove also wrote "Tribute Maidens" (Vol I) and "Those Who Lose" (Vol IV).
A fifth Haven story collection "CoDominium: Revolt on War World" set during the CoDominium period was also published. This contained the Turtledove short story "Hang Together".
In 2007, John F. Carr the editor or the short story collections, published a new novel The Battle of Sauron which depicts the defeat of the Saurons and the initial attack of Haven by an escaping Sauron warship. Carr has indicated he will re-issue the short stories in new collections along with new material beginning with "War world : Discovery" (2010). These will be published in story chronological order as the previous collections gathered stories set over several hundred years of Haven history.