Fighting in the Hornwood
Fighting in the Hornwood takes place in 299 AC in the Hornwood lands of the North during the War of the Five Kings. Fighting occurs between House Bolton, led by the Bastard of the Dreadfort, Ramsay Snow, on the one side, and Hornwood men loyal to Lady Donella Hornwood and Manderly men led by Lord Wyman Manderly of White Harbour on the other side.
Following the assault and capture of Ned Stark in King’s Landing, his son Robb Stark raises a Northern host and marches south into the Riverlands. House Hornwood answers the call to banners, and Lord Halys of the Hornwood and his son and heir, Daryn Hornwood, march with him. Lord Halys Hornwood is killed by Westermen at the Battle on the Green Fork whilst his son Daryn dies at the hands of Ser Jaime Lannister at the Battle of the Whispering Wood. This leaves Halys’ widowed wife, Lady Donella Hornwood, as the head of the house but without an heir, as Daryn was Halys’ and Donella’s only child. 
Following Lord Halys’ a dispute arises among the Northern lords over the Hornwood lands. Lord Wyman Manderly offers to marry Donella, who is a cousin of his and a Manderly by birth. Alternately he offers to marry his son, Wendel, to Donella. In either case, this would allow the Manderly’s to control the Hornwood lands. Mors “Crowfood” Umber also offers to marry Donella, which would allow House Umber to take control of the Hornwood lands.
House Glover is fostering Larence Snow, the bastard of Halys Hornwood, at Deepwood Motte and seek for him succeed Halys once legitmised by King Robb Stark. Despite having no succession claim, House Bolton’s lands border those of the Hornwoods and they also seek the Hornwood lands. The bastard of Lord Roose Bolton, Ramsay Snow, is known to be raising a force of men at the Dreadfort, who Donella hopes are meant for the war in the Riverlands rather than any fighting in the North. House Tallhart announces their claim as well. The wife of Leobald Tallhart is a Hornwood and they have two sons, both nephews to Donella. Leobald suggests sending his younger son, Beren, to be fostered by Donella, who could take the surname Hornwood once being named heir and succeed her upon her death. Maester Luwin concluded Beren Tallhart is the best solution to the Hornwood succession crises, but Ser Rodrik Cassel, the Castellan of Winterfell, argues that the child is only a boy and could easily be displace by the armies of House Bolton or House Manderly.
Houses Flint and Karstark have blood ties to House Hornwood through the female lines and so all may be potential claimants to their lands. It is also suggested that perhaps Lady Donella could be required by Robb to marry a riverlord instead in order to strengthen the alliance between the North and the Riverlands. Maester Luwin suggests a member of either House Blackwood or House Frey.
Fighting in the Hornwood Forest
After Donella leaves Winterfell to return home she is captured en route to Hornwood Castle by Bolton men led by Ramsay Snow who have invaded the Hornwood lands. Ramsay Snow forcefully married her that same night in order to claim her lands. In response, Lord Wyman Manderly ordered an invasion of the Hornwood and captured Hornwood castle to prevent the Boltons from taking it. 
Ramsay Snow forces Donella to name him his heir and locks her in a tower. Fighting breaks out in the Hornwood Forest between Manderly and Bolton men. In response Ser Rodrik leads a force of men from Winterfell to capture Ramsay. Ramsay is supposedly killed after Rodrik arrives, although it was later revealed that in fact Ramsay’s friend Reek was killed instead, wearing Ramsay’s clothing. It is revealed that Donella Hornwood had starved to death in the tower and was forced to eat her own fingers. 
Despite the supposed death of Ramsay, the Northerners of Winterfell still fear Roose Bolton will press a claim on the Hornwood lands. Rodrik also states that fighting is ongoing between Bolton and Manderly men as he lacks a strong enough force to halt them.
Later on it is revealed Ramsay is still alive. Following the betrayal of House Stark by the Boltons and Freys, Lord Roose Bolton is named Warden of the North and his son Ramsay is legimitamised. Ramsay presents himself from this point onwards as Lord of the Hornwood and Heir to the Dreadfort.  Wyman Manderly’s son Wylis was captured in the Riverlands, and Wyman agrees a deal with the Lannisters. In exchange for executing the Hand of King Stannis, Davos Seaworth, who is at White Harbour to seek an alliance, withdrawing from the Hornwood lands and submitting to Roose Bolton, Wylis will be released. Sometime after this agreement is made the Manderlys release Hornwood castle and the Hornwood lands to the Boltons.
- A Game of Thrones, Chapter 53, Bran VI.
- A Clash of Kings, Chapter 16, Bran II.
- A Clash of Kings, Chapter 26, Arya VI.
- A Dance with Dragons, Chapter 12, Reek I.
- A Dance with Dragons, Chapter 41, The Turncloak.
- A Dance with Dragons, Chapter 46, A Ghost in Winterfell.
- A Clash of Kings, Chapter 35, Bran V.
- A Dance with Dragons, Chapter 20, Reek II.
- A Dance with Dragons, Chapter 28, Jon VI.
- A Dance with Dragons, Chapter 32, Reek III.
- A Dance with Dragons, Chapter 37, The Prince of Winterfell.
- A Feast for Crows, Chapter 17, Cersei IV.
- A Feast for Crows, Chapter 24, Cersei V.
- A Dance with Dragons, Chapter 58, Jon XII.