The Protector's War is a 2005 alternate history, post-apocalyptic, science fiction novel written by S.M. Stirling and is the second novel in the Emberverse series. The Protector's War describes the events in August 2006 in England and at sea and from March through October 2007 in Oregon, approximately eight years after the Change which altered the laws of physics. Clan Mackenzie and the Bearkillers, led by Juniper Mackenzie and Mike Havel, respectively, have carved territories in the Willamette Valley for their groups. They have become bitter rivals with the Portland Protective Association (PPA), led by the Armingers. The book describes the preparations of the PPA for a war of conquest against the other communities of the Willamette Valley, the communities' actions in response, and the arrival of three English refugees whose coming will help shape events in Oregon.
John Hordle and Alleyne Loring help rescue Alleyne's father, Sir Nigel, who has been imprisoned at Woburn Abbey by King Charles III because Sir Nigel's loyalty is questioned. Nigel refuses to do anything that might start a civil war. The party is intercepted by troops loyal to Charles. After Nigel defeats the leader, Anthony Knolles, in single combat the two Lorings and Hordle proceed toward the coast and self-imposed exile.
On Mar 17, 2007, Mike Havel is hosting a party to celebrate the anniversary of the Change. Attendees include Abbot Dmowski of the Order of the Shield of Saint Benedict, Juniper Mackenzie of Clan Mackenzie and Luther Finney of the Corvallis City State. Juniper has brought her son Rudi to the party. Rudi is also Mike's son, a perennial sore point between Mike and his wife Signe. Mike and Ken Larsson discusses the problem Rudi's parentage has on a feudal society like that of the Bearkillers. They also discuss Ken's conclusion that the Change was caused.
The Lorings, Hordle and their escort encounter a band of brushwood men and have to fight for their lives. They prepare to travel by boat downriver to a port where the Tasmanian vessel Pride of St Helens awaits.
En route to Dun Juniper, Juniper's group hears baying hounds. Astrid Larsson and her Rangers make a stand and tell a group of refugees to contiunue fleeing. After the refugees flee, Baron Eddie Liu and a group of Liu's soldiers arrive. Liu insults Astrid and wrongly claims to be on Portland Protective Association territory. He apparently expects reinforcements and is disconcerted when his men are intercepted by Juniper and her Mackenzies. He retreats, swearing revenge against the Clan.
After a training workout, Mike Havel receives an intelligence briefing from Eric Larsson. Mike learns that the Portland Protective Association is building more castles south of Portland, is stocking up on food and that the Protector is planning to declare his daughter Mathilda as his heir and that Arminger has been spending a lot of time with recently arrived Tasmanians. Afterward, Mike and Signe argue about Mike having fathered Rudi Mackenzie, but the argument settles nothing.
Dennis Martin works on a wooden frieze for Sutterdown. Sam Aylward assists a sheep giving birth then goes home for dinner. The guard on duty reports that someone has stolen a sheep. Sam calls out reinforcement in case the theft is a distraction and organizes a patrol to recover the animal. A short while later his daughter arrives at Dun Juniper to notify Juniper Mackenzie that Sam has found something that Juniper needs to see.
Nigel Loring, Alleyne Loring and John Hordle assist in scuttling a supertanker. They soon find themselves being pursued by Cutty Sark, but outrun the other vessel in a storm. When the storm ends, Captain Nobbes of Pride of St Helens realizes that a Cutty Sark has been attacked by pirates and intervenes. Nigel discovers that Prince William is aboard Cutty Sark. William asks Nigel to return to England, but Nigel declines, saying that he does not want to put William on the throne by sword.
Sam Aylward and his search party catch up with the sheep stealers and Sam realizes that they are the refugees that the Rangers and Mackenzies had saved earlier. Sam sends the guarded message about them to Juniper. He takes the refugees back to his home at Dun Fairfax. Juniper comes to Sam's home and talks to the people, who have been taught to fear "witches." The refugees give her documents and maps one of their group took from Eddie Liu's desk. Sam examines them and says that they are written in an Altendorf substitution code. One of the refugees says that Liu had said that it all depended on the Brits and Tasmanians.
Mike and Signe Havel set themselves up as decoys in an attempt to trap a bandit named Crusher Bailey who has been operating successfully in the PPA-Bearkiller border area. They stop at Crossing Tavern, an inn operated by Arvand Sarian. Bailey takes the bait and attacks the Havels after they leave the inn the next morning. Mike, Signe and a military apprentice hole up in an abandoned store. The fight a defensive battle which they are on the verge of losing when help arrives calling, "St. George for England!"
Following Clan Mackenzie's periodic bow qualifications, Laurel Wilson arrives at Dun Juniper to apply for admittance to the Mackenzies for her group of about eighty which had been struggling to survive. She is assured by Juniper Mackenzie that admission is virtually certain. Juniper then meets with her advisers to discuss the war against the Portland Protective Association they all know is coming. They decide to strike an early blow against the Protectorate.
Crusher Bailey and his bandits flee. Nigel Loring, Alleyne Loring and John Hordle introduce themselves and, while Will Hutton and Bearkiller troopers provide a block against Protectorate forces, retreat with Mike Havel and the others. The British help the Bearkillers find and annihilate the bandit camp; the Mackenzies happen by at the right moment. The Lorings and John Hordle meet the Mackenzies after the fight and are reunited with Sam Aylward. The party returns to Crossing Tavern where Mike hangs the bandits and accepts the feality of Arvand Sarian.
Much of the following chapters is told in flashbacks.
Juniper Mackenzie leaves Dun Juniper to celebrate Beltane in Sutterdown. She leaves Chuck and Judy Barstow behind because having them all absent might seem suspicious. Dennis Martin and his family are part of Juniper's group and he brings the frieze he carved. As Beltane winds down, Juniper and Sam Aylward discuss some options and gather a group around them.
The Mackenzies move through the mountains in three groups toward their objective of disrupting activities of the Portland Protective Association inside its own borders. En route, one of the groups encounters Protectorate foresters and a short battle ensues. The Mackenzies raid a border outpost designed to keep people from leaving the Protectorate territory.
The flashback narratives end.
The Dúnedain Rangers decide to establish their own base of operations at Mithrilwood. At Sutterdown's horse fair Juniper Mackenzie convinces Tom Brannigan to reject an offer from Thomas Turner and Agnes Kowalski of the Corvallis City State that would have indebted Sutterdown. Later, a man tries to sell an abused horse to Mike Havel. Rudi Mackenzie finds the horse attractive and Signe Havel eggs him into riding the animal. Rudi addresses the horse as Epona and rides her. When he returns and dismounts Mike hugs him and calls him his son. Juniper Mackenzie is angry. Signe tries to apologize to Juney but Juney rebuffs her. Mike later tells Signe that another such action will result in their separating.
- All remaining state government in Oregon has completely collapsed.
- Salem, the former capital of Oregon is a ruin and home to bandits.
- France and Spain are virtually depopulated; the British at Gibraltar survived because they were able to block the access route from Spain. The English are gradually colonizing France and Spain.
- Norway survived the dying time, is prospering and has claimed what was Germany.
- The population of Italy is about 260,000:
- Ten thousand in the Alps
- Fifty thousand in Umbria
- Two hundred thousand on Sicily
- Most of Europe's surviving population is on islands.
- Worldwide, with few exceptions, any city of more than 250,000 people is dead, with a dead zone around it. The bigger the city, the bigger the dead zone. Portland is one of the few exceptions.
- The North Island of New Zealand suffered because of the population density of Wellington and Auckland; the South Island fared better with its one population center of Christchurch. The nation has formed a federation.
- Australia suffered, but Tasmania survived and has established itself as a free republic.
- Singapore survived as the entire population organized and moved into the countryside.