A trilogy by S.M. Stirling, in which the entire island of Nantucket is sent back in time to the late Bronze Age by a mysterious dome of light. "The Event" also brings along the Eagle, a Coast Guard training vessel—a mixed blessing for Nantucket, for while the ship and its crew prove invaluable in saving the island from starvation, one of the officers, William Walker gathers a band of followers and hijacks a ship for England, where he sets himself up as a warlord among the Indo-European tribes of the area. For obvious reasons, the people of Nantucket are not pleased with this, and the Town Meeting, under the leadership of former police chief Jared Cofflin and Marian Alston, captain of the Eagle, sends a force after him.The first book, Island in the Sea of Time, covers the first couple of years, from the Event up to the Battle of the Downs, where Walker and his local allies meet the expeditionary force from Nantucket and their local allies.The second book, Against the Tide of Years, sees Nantucket facing a threat from Tartessos, a kingdom in Spain that has been rapidly "modernizing" under the rule of one of Walker's friends. Contact is made with the kingdoms of Mycenae and Babylon, and an expedition prepares to follow in the footsteps of Lewis and Clark.The third book, On the Oceans of Eternity, brings with it the end of the war.There is also a short story, "Blood Wolf", set in the same milieu, but about a generation later.The series is tenuously connected to the Emberverse, which covers what happened in the world Nantucket left behind.
Aerith and Bob: As Nantucket grows more racially integrated, with lots of Iraiina and Fiernan immigrants, as well as the odd Native American, names like "Llandaurth Witharaxsson" become increasingly common.
Anti-Villain: Isketerol, merchant adventurer-turned-king of Tartessos. When the Nantucketers invade Tartessos in the third book, they were undoubtedly expecting to find a totalitarian hellhole like the society Walker has established in Greece; what they find instead is a society which is a perfect example of Fair for Its Day, as Isketerol has made literally revolutionary improvements in all areas of Tartessian society, not just the military, and has put huge outlays of time, effort and money into making life better for the ordinary people.
Artistic License - Linguistics: Sun People language. Although words themselves are mostly fine, what little grammar we see is more like English than Lithuanian (or PIE reconstructions.) "Diasas," for example, is used to mean both male and female slaves, even though it most probably would've been two distinct words (to match grammatical gender) in an early Indo-European language.
Chekhov's Skill: Quite a few, but among the prominent ones, Doreen Rosenthal being an astronomer comes in very handy when convincing the elders of Swindapa's tribe, who are basically the caretakers of Stonehenge, that the Nantucketers are friendly.
Critical Staffing Shortage: The island of Nantucket suddenly finds itself short-staffed in every single aspect of infrastructure after the island is thrown back in time to the Bronze Age.
Egopolis: Walker's Alban base is called "Walkerburg." The capitol of his Greek territories is called "Walkeropolis."
Enemy Mine: Despite the antagonisom between all sides, Nantucket, Walker's faction, and the Tartessians all exchange information and work together to contain a potential epidemic that could have wiped all of them out.
Pamela Lisketter is a very brutal deconstruction of the trope.
Heroic BSOD: While not precisely a hero, Isketerol undergoes one of these when he realizes that in the future where Nantucket came from, experts aren't sure his nation even existed.
The king of Bablyon undergoes a milder one, assuaged by assurances that Nantucket's advances were only possible with thousands of years more time than the Babylonians had had to work with, and the foundation that Babylon itself helped to build. It's these assurances, diplomatically wielded, that establish Babylon as the first really powerful ancient civilization with which Nantucket is able to forge an alliance.
Heteronormative Crusader: In the first book, Marian Alston and Swindapa have to contend with a bitchy local woman who objects to homosexuality. Since Alston is the head of Nantucket's military, the woman's complaints are pretty much ignored by everyone else.
Historical-Domain Character: A few - the king of Babylon, the Pharaoh, and maybe some of the Achaean and Trojan characters, depending on what you think of Homer's accuracy...
Human Sacrifice: The followers of the Jaguar God have this in mind for their captives.
I'm a Humanitarian: Some of the Lisketter group meet their ends this way at the hands of the Mesoamericans, one almost immediately after capture since the Jaguar God followers apparently have a thing for freshly-drained blood.
And at one point Alice Hong mentions that she enjoys the taste of "long pig" and "long veal steak" - the implication being that she has killed and eatenchildren.
Malcolm Xerox: Sam McAndrews. He betrays Nantucket in the hopes that Walker will let him prop up the nearest African civilization. This turns out to be Ancient Egypt, whose people are more closely related to the Arabs than anyone that might be called "black". McAndrews isn't exactly thrilled.
Nice Job Breaking It, Hero: Pamela Lisketter's group aren't heroes except in their own minds, but their attempt to prepare the Mesoamericans against Nantucket/European encroachment winds up infecting the Mesoamericans with mumps and wiping out their civilization.
Royals Who Actually Do Something: Several. William Walker is his own top general, and Kashtiliash and Raupasha take a direct hand in fighting for their respective countries.
Slavery Is a Special Kind of Evil: The Republic of Nantucket takes a very dim view of slavery, as shown by the fact that almost all of its major warships are named after Civil War heroes or abolitionists. Given that one of its most prominent citizens is a former slave, this probably shouldn't be surprising. Naturally, the Big Bad, of the series, William Walker, heavily employs slavery in his empire.
Starting New Life: Swindapa leaves Alba behind when it is taken over by the Iraiina, and heads to Nantucket, where she becomes Marian Alston's assistant (and later, her lover.) She's later able to return to her people, but she's changed quite a bit by that point.
Schizo Tech: Bronze axes, ultralights with napalm, katanas, breech-loading rifles, wooden frigates, bicycles, an airship... the list goes on.
Shown Their Work: Bronze Age archaeology has enough competing theories that it would be impossible to be accurate to all of them, but the series is nonetheless impressive in this regard.
Strange Syntax Speaker: The second book features a scene where Swindapa and her Fiernan peers converse in their own language. Their conversation is presented in English, but even that requires a further translation, because the Fiernan language is loaded with metaphors and figurative language.