Angmar War

The Angmar War was a centuries-long struggle between  Arnor and the forces of Angmar, led by the Witch King, a servant of Sauron.
It resulted in the destruction of the Northern Kingdom, reduced to the secretive Dunedain Rangers, a depopulation of Eriador (and of parts of Rhovanion), an infestation of Orcs, Goblins and Trolls in the Misty Mountains and Ettenmoors,all to the favor of Sauron, but also in the destruction of Angmar itself, and the entombment of its King and the other eight Nazgûl, to the Dark Lord's detriment.
== Background ==
Over a millennia since Sauron's defeat near the end of the Second Age, evil things began to multiply again. Sauron's servants, the Nazgûl, reappeared, harassing both the South and North Kingdoms.
In the south, they eventually captured the city of Minas Ithil while in the north the Witch King, the leader of the Nazgul, established himself in the lands around the mountains of Angmar, to the north of the Misty Mountains.
After the death of King Earendur, the northern kingdom of Arnor was split into three parts: Arthedain, Cardolan and Rhudaur, each ruled by one of Eärendur's sons. There was often strife between the three kingdoms, usually over control of the Weather Hills and the Palantir of Amon Sul.
When Malvegil of Arthedain became king in 1272 Orcs came down from the North and began to trouble the region. Around TA 1300, the Witch-king founded the kingdom of Angmar in and around the Mountains of Angmar. This land became populated with Orcs and evil Hill-Men, and began attacking Rhudaur and Cardolan. This Witch-king was only later identified as in fact the chief of Sauron's Ringwraiths.
== Early Wars ==
Argeleb I of Arthedain claimed the kingship of all Arnor, the line of Isildur having failed in Cardolan and Rhudaur. In Cardolan Argeleb was recognized as king, though it also kept its own princes. Rhudaur however resisted the claim, and openly allied with Angmar. Argeleb fortified the Weather Hills, but was killed in battle with Rhudaur and Angmar in TA 1356.
His son, Arveleg I, received help from Cardolan and Lindon, and was able to drive the enemy back from the Weather Hills. After this the men of Arthedain and Cardolan held, for many years, a frontier along the Weather Hills, the East Road and the lower Hoarwell. During this period the Witch-king besieged Rivendell, but failed to take it.
In TA 1409, the Witch-king launched a massive assault upon Arnor, circling around the Dúnedain defences to invade Cardolan from the south. Causing huge destruction, the host of Angmar marched north to Amon Sûl. The great watchtower was taken and destroyed, although its palantír was saved and brought to Fornost. In this war both Arveleg and the last Prince of Cardolan perished. The remaining Dúnedain of Rhudaur were slain or driven west, while those of Cardolan held out only in Tyrn Gorthad and the Old Forest. Fornost meanwhile was beset by the armies of Angmar, but Cirdan brought reinforcements out of Lindon, enabling the young king Araphor to repel his foes from the North Downs.
Arnor had been weakened hugely but the Witch-king was unable to press home his advantage because, at this point, the Elves unleashed their remaining strength upon Angmar. Elrond persuaded King Amroth to send a force of Galadhrim over the High Pass to Rivendell. Together with their kinsfolk of Lindon, they dealt such a blow to Angmar that it was left in a weakened state for centuries.
Around this time, Angmar also extended east into the upper Anduin Vales where it was contested by Thranduil's Woodland Realm, which launched at least one failed assault against Angmar and Gundabad. The Elven-queen, protecting and presumably hiding her young son, Legolas, was captured and taken to Gundabad and killed, which resulted in Thranduil's withdraw from the war.
Arnor, however, was unable to recover its former strength. Much of its territory was already deserted, prompting Argeleb II to grant The Shire to the Hobbits (who themselves fled their original settlements in the Gladden Fields for fear of Angmar's power) in TA 1601. 
In the seventeenth century a Great Plague came from out of the East, devastating Rhovanion and Gondor. While Arthedain was relatively unaffected, Cardolan suffered greatly and the remaining Dúnedain in Tyrn Gorthad perished. The Hobbits of the Shire also saw great loss, but their numbers recovered in time. In the wake of the Plague, evil spirits came down out of Angmar and Rhudaur and reanimated the corpses of the Dúnedain of the Barrow-downs.
== The Fall of Arnor ==
The North-Kingdom nonetheless had peace for a time, but in the nineteenth century Angmar renewed its attacks. King Araval was slain fighting in Cardolan in TA 1851 and, in the same year, Gondor was attacked by the Wainriders for the first time. Suspecting that these attacks might be being coordinated, the two kingdoms finally brought to an end their years of estrangement. In TA 1940, Arvedui heir to the sceptre of Arnor, wedded Fíriel, the daughter of Ondoher of Gondor. Hoping to save Arnor from Angmar, Arvedui staked his claim to Gondor, by right of his descent from Elendil and by that of his wife. The lords of Gondor however were not for reunification. Arvedui did not press his claim, and the steward Eärnil maintained good relations with Arnor, promising them aid against the continuing attacks of Angmar. Arvedui succeeded his father in TA 1964, but Arnor's strength was fast dwindling.
After centuries of conflict, in T.A. 1973 messages were sent to King Eärnil II of Gondor that they were in great straits, and that Angmar was preparing its final assault. The King sent his son Prince Eärnur, with a fleet of ships to Lindon to aid the northern Dunedain.
It was too late. In TA 1974 the Witch-king amassed his forces and launched a final assault on Arthedain. The Witch-king attacked during the harsh winter weather and took Fornost. The remnants of the Arnorian forces fled west over the river Lune but Arvedui held out for a short time in the North Downs. He and a few surviving companions were eventually forced to flee to the abandoned mines of the northern Ered Luin. With their food running out, they sought refuge with the Lossoth of Forochel. Receiving word of the King's whereabouts, Cirdan sent a ship to the Icebay to rescue him. Against the advice of the Lossoth chieftain, Arvedui boarded the ship, which that night was wrecked by a storm from the North. Arvedui drowned, and with him were lost the palantíri of Fornost and Amon Sûl. His Ring, however, was given to the Lossoth and therefore survived, eventually being reacquired by the Dunedain, who had since become Rangers in Eriador.
== Domain of Angmar and defeat ==
The Witch-king now sat the throne in the king's palace, and the realm of Angmar reached the zenith of its power.
Earnil sent his son Earnur, who mustered a great army, including Eotheod horsemen. The Gondorian force was put to sea. Arriving at 1975, there were so many ships that the fleet filled Forlond, Harlond, and the Grey Havens; amazing the people of the North, even though this was but a small part of Gondor's strength. Círdan summoned the Noldor, Sindar and what remained of the Men of Arnor, then the allied host marched across the Lune to challenge the occupiers of Fornost. The Hobbits claimed to have sent archers to aid in the battle, as well.
Círdan and Earnur, son of the steward, combined their forces, along with the remnant of Arnor's army, in the greatest joint Elf-Man army since the War of the Last Alliance; this great Host of the West re-crossed the River Lune and marched northward. 
The Witch-king, confident and proud after his recent victories, did not prepare for a siege, but sent his army out to face the Host of the West. The Men and Elves came down from Hills of Evendim and engaged the forces of Angmar in the plains between Nenuial and Fornost. The Host of the West had the better of the fighting, and the Angmarim began to retreat back to Fornost.
Suddenly, out of the north, came the main body of the Gondorian cavalry, which had passed around the Hills and outflanked the enemy. They fell upon the Angmarim and scattered them in a great rout. The Witch-king gathered what troops he could and tried to lead them back to Angmar but was overtaken by the cavalry of Gondor led by Earnur.
At the same time a force of Elves led by Glorfindel came up out from Rivendell and the remnants of Angmar's army were utterly destroyed, but the Witch King fled back to Carn Dum. Angmar's mountainous strongholds there and in Gundabad would not fall for over another 500 years.
In fact, being pushed back from Eriador seem to have led the Witch King to focus his efforts on attacking the Wilderland. In 2340, an Orc raid into Greenwood resulted in the deaths of at least one pair of Silvan Elves. The Elvenking Thranduil had the Orcs hunted down, and adopted the oprhaned Elf, Tauriel. In 2480, Orcs and Goblins from Angmar began to settle the passes and caverns in the Misty Mountains, including the since-deserted Dwarven realm of Moria and the tunnels near the High Pass (which became Goblintown).
Angmar's power also had indirect outcomes: the Balrog of Moria was awoken during its reign, resulting in the Dwarves' flight, and the One Ring was found in the Gladden Fields by two Riverfolk Hobbits, Deagol and Smeagol, with the latter killing the former and taking the Ring into the caves underneath Goblintown.
Meanwhile, in the South, Boromir I of Gondor defeated the forces of Minas Morgul in the south, causing the eight other Nazgul to flee to Angmar.
Eventually, Carn Dum fell and the Witch King and all eight other Nazgul were defeated and entombed with all their possessions within the High Fells of Rhudaur.
== Aftermath ==
The defeat of Angmar ushered-in the Watchful Peace, which lasted for 400 years before the Necromancer appeared and the War of the Ring was eventually begun.
The Angmar War left Arnor destroyed, with only a remnant of the Dunedain surviving as Rangers. Eriador was largely depopulated, leaving Lindon, The Shire, Breeland and Rivendell as the main settlements.
Orcs and Goblins maintained their strongholds in the Misty Mountains, most notably in Moria (under Azog), in Gundabad (under his son Bolg) and in Goblintown under the Goblin King. Another Goblin domain was in Mount Gram (presumed to be in the Ettemoors) under Golfimbul, who led an invasion into Eriador and the Shire, where he was defeated by Bandobras Took in the Battle of Greenfields. Trolls resided in the Ettenmoors, and when the evil of the Necromancer grew, three such Trolls - Bill, Tom and Bert - ventured south into a forest on the outskirts of Staddle which became Trollshaws. These Orc and Troll population would prove instrumental to Sauron's cause in the Quest of Erebor and the War of the Ring.
In 2940, Sauron's initial objective was to reclaim the lands of Angmar so as to defeat the Elven kingdoms of Greenwood, Lorien and Rivendell. He tried to stop a Dwarvish quest to reclaim Erebor, which he intended to capture in order to secure Angmar's eastern flank, and sent two armies from Moria and Gundabad to take it from the Dwarves. This intention was foiled in the Battle of the Five Armies.
Nevertheless, the residue of Orcs and Trolls in the North was used by Sauron to attack Lorien and the Woodland Realm, unsuccesfully, during the height of War of the Ring. Bree and the Shire were also harassed to a lesser extent.