Question: The fictional deity Sigmar Heldenhammer is the patron deity of this faction whose cultures are based on what real-world empire?

full_context: Document 1: The Empire (Warhammer): In Games Workshop's "Warhammer Fantasy" fictional universe, The Empire is one of the human political factions and armies, and is featured in many games and novels. In terms of location, language, culture, and society, it is clearly based on the real-world medieval Holy Roman Empire.
Document 2: The Story of Sigurd the Volsung and the Fall of the Niblungs: The Story of Sigurd the Volsung and the Fall of the Niblungs
Document 3: Midkemia: Midkemia is a fictional world created by a fantasy role-playing group and popularized by Raymond E. Feist where most of the Riftwar books take place. Only the Empire Trilogy, which was co-written with Janny Wurts, takes place entirely on Kelewan, another world connected to Midkemia by magically created rifts in space.
Document 4: Sigmar: Sigmar Heldenhammer is a fictional deity in the "Warhammer Fantasy" setting. He is the patron deity of The Empire. Before he became a god, Sigmar was a man, albeit an exceptional, perhaps even superhuman one. The young chieftain of the Unberogens who lived 2,500 years before the present day of the Warhammer universe, he united the barbarian human tribes into what would become the mightiest human nation – the Empire. His sign is a twin-tailed comet or a war hammer.
Document 5: Heremod: Heremod (Proto-Norse: *"Harimōdaz" , Latin form: Heremodius) is a legendary Danish king and a legendary king of the Angles who would have lived in the 2nd century and known through a short account of his exile in the Old English poem "Beowulf" and from appearances in some genealogies as the father of Scyld. He may be the same as one of the personages named Hermóðr in Old Norse sources. Heremod may also be identical to Lother (Latin Lotherus) in Saxo Grammaticus' "Gesta Danorum" (Book 1) or the same history may have been applied to two originally separate figures.
Document 6: Sigmar (disambiguation): Sigmar is a fictional deity in the "Warhammer Fantasy" setting.
Document 7: Shattered Empire: Shattered Empire is the first expansion to the board game "Twilight Imperium", both of which were designed and published by gaming company Fantasy Flight Games. It was released in December 2006.
Document 8: Space Marines (Warhammer 40,000): In the table-top wargame "Warhammer 40,000", the Adeptus Astartes (also known as the Space Marines) are genetically modified superhuman soldiers, the elite warriors of the Imperium of Man. Space Marines have been one of the starter armies in every box edition of Warhammer 40,000, Space Hulk, and Epic. They also feature heavily in other Games Workshop products, such as books, films, and video games, and are central to the universe's setting.
Document 9: List of thunder gods: Polytheistic peoples of many cultures have postulated a thunder god, the personification or source of the forces of thunder and lightning; a lightning god does not have a typical depiction, and will vary based on the culture. In Indo-European cultures, the thunder god is frequently known as the chief or king of the gods, e.g. Indra in Hinduism, Zeus in Greek mythology, and Perun in ancient Slavic religion; or a close relation thereof, e.g. Thor, son of Odin, in Norse mythology. This is also true of Shango in Yoruba religion and in the syncretic religions of the African Diaspora, such as Santería (Cuba, Puerto Rico, United States and Candomblé (Brazil).
Document 10: Hammer of Thor (monument): The Hammer of Thor is a 3.3 m tall, t-shaped, man-made rock formation, located along the Arnaud River in the Ungava Peninsula, Quebec, Canada. It was discovered in 1964 by an archaeologist who thought it was erected by Vikings. He named it "The Hammer of Thor", in reference to the hammer-wielding Thor of Norse culture. Today some scholars believe that it is more likely to be an artifact of Inuit culture, an inuksuk or stone landmark.
Document 11: Holy Roman Empire: The Holy Roman Empire (Latin: "Sacrum Imperium Romanum" ; German: "Heiliges Römisches Reich" ) was a multi-ethnic complex of territories in central Europe that developed during the Early Middle Ages and continued until its dissolution in 1806. The largest territory of the empire after 962 was the Kingdom of Germany, though it also came to include the Kingdom of Bohemia, the Kingdom of Burgundy, the Kingdom of Italy, and numerous other territories.
Document 12: Chaos (Warhammer): In Games Workshop's "Warhammer Fantasy" and "Warhammer 40,000" fictional universes, Chaos refers to the malevolent entities which live in a different timespace, known as the Warp in "Warhammer 40,000" and as the Realm of Chaos in "Warhammer Fantasy". The term can refer to these warp entities and their influence, the servants and worshippers of these entities, or even the parallel universe in which these entities are supposed to reside. The most powerful of these warp entities are those known as the Chaos Gods, also sometimes referred to as the Dark Gods, Ruinous Powers, or the Powers of Chaos. Similarities exist between the Warhammer idea of Chaos and the concept of Chaos from Michael Moorcock's Elric saga, which also influenced D&D's alignment system. Further similarities can be seen with the godlike extradimensional Great Old Ones of horror writer H. P. Lovecraft's stories.
Document 13: Svinfylking: The Svinfylking, Old Norse for 'Swine Array' or 'Boar Snout', was a version of the wedge formation used in Iron Age Scandinavia then by the Vikings, and by the Germanic peoples during the Germanic Iron Age where it was known as the "Schweinskopf" or 'Swine's Head'. Its invention was attributed to the god Odin.
Document 14: Horus Heresy (fictional event): The Horus Heresy is a cornerstone event in the far future fictional universe created by Games Workshop as the campaign setting for its "Warhammer 40,000" miniatures wargame. It is a relatively short but devastating galaxy-spanning civil war that engulfs the nascent galactic empire of the Imperium of Man early in the 31st millennium of the universe timeline; the war is a major cause of the science fantasy universe's dystopian environment. Initially described in wargame supplements published in 1988, and used as the setting for a 1989 "Epic"-branded tabletop miniatures wargame, it has been utilised since as background for several of Game Workshop's products.
Document 15: Last Empire-War Z: ""Last Empire - War Z "" is a popular freemium Massively Multiplayer Online strategy game developed and published by IM30 Studios.It was launched in August 2015 and then spread all over the world, it became popular among players with a shocking speed, now having over 80 million downloads and is available in over 220 countries. It is the Google play“Best of Game 2016”. ""Last Empire- War Z"" has been recommended to globe twice and to districts for several times. It always takes a high rank in App download list in most countries and is one of the best strategies games that was beloved by players. High rates and good comments mean it attracting more and more worldwide players.However, despite the great success it has achieved, many players would complain about having difficulties dealing with all kinds of bug when enjoying the gameplay, and the constant ignoration from the game when trying to report the problems they have came up with. It seems that more and more players have shown their dissatisfaction about the game itself as it always tend to release new updates in order to earn more money instead of responding to players or paying attention on solving the bugs. Also, the game's system is almost the same as another strategy game - Clash of Kings.
ground_truth: Holy Roman Empire