|Duke of Brittany|
|Predecessor||Hoel II & Hawise|
|Regent||Hoel II (1072–1084)|
|Died||13 October 1119|
(m. 1086;died 1090)
|Father||Hoel II, Duke of Brittany|
|Mother||Hawise, Duchess of Brittany|
Alan IV (c. 1063 – 13 October 1119) was Duke of Brittany from 1072 until his abdication in 1112. He was also Count of Nantes (from c. 1103) and Count of Rennes. His parents were Duchess Hawise and Duke Hoel II.  He is also known as Alan Fergant. Through his father, he was of the Breton House of Cornouaille dynasty (Breton: Kerne dynasty). He was the last Breton-speaking Duke of Brittany. 
A traditional rivalry between Brittany and Normandy continued at the close of the 11th century. The Breton-Norman war of 1064–1065 was the result of William the Bastard, Duke of Normandy (later to become known as William the Conqueror) support of rebels in Brittany against Alan's maternal uncle, Conan II.
Conan II died in late 1066 during a campaign in Anjou, and was succeeded by Alan's parents, Conan's sister, Hawise, and her husband, Hoel II. Alan became Duke in 1072, but being a minor, Hoel ruled as regent from Hawise's death in 1072 until Alan reached his majority in 1084. [lower-alpha 1]
To prevent further hostilities during his invasion of England, William I married his daughter Constance to the new duke Alan in 1087.  The marriage ceremonies may have taken place in Bayeux in Normandy. William of Malmesbury wrote that Constance was unpopular at the Breton court because of her "severe and conservative" manner. However, Orderic Vitalis wrote that as duchess Constance did all she could to further the welfare of the Bretons, who grieved deeply at her death in 1090.
In 1092, Alan IV donated property to the abbey of Redon by charter, and by 1093 married Ermengarde of Anjou, as a political alliance with Fulk IV of Anjou to counter Anglo-Norman influence.
Duke Alan IV's cousin Geoffrey I Boterel (eldest brother of Alan Rufus) died on 24 August 1093 in battle at Dol while in rebellion against the Duke.
Between 1101 and 1104, Alan's younger brother, Count Matthew II of Nantes, died without issue and his county passed to Alan.
Alan IV abdicated as duke in 1112. The former duke retired to the monastery of Redon, where he died in 1119.
In 1098 Alan went on the First Crusade,  as part of the army of Robert Curthose, leaving Ermengarde as his regent, and returned in 1101.
Alan IV married Constance in 1087. Constance died in 1090. William of Malmesbury alleges that her husband, Alan, had their servants poison her.  They had no children.
Alan's second marriage was to Ermengarde of Anjou in 1093.  With Ermengarde he had three children:
Alan and Ermengarde were separated upon his abdication as duke in 1112.
He had two illegitimate sons:
Alan IV died in 1119 at the monastery of Redon, where he had retired after his abdication in 1112, and separation from his wife Ermengarde. His only surviving son, Conan III succeeded him.
The Duchy of Brittany was a medieval feudal state that existed between approximately 939 and 1547. Its territory covered the northwestern peninsula of Europe, bordered by the Atlantic Ocean to the west, and the English Channel to the north. It was also less definitively bordered by the river Loire to the south, and Normandy, and other French provinces, to the east. The Duchy was established after the expulsion of Viking armies from the region around 939. The Duchy, in the 10th and 11th centuries, was politically unstable, with the dukes holding only limited power outside their own personal lands. The Duchy had mixed relationships with the neighbouring Duchy of Normandy, sometimes allying itself with Normandy, and at other times, such as the Breton-Norman War, entering into open conflict.
Geoffrey I, also known as Geoffrey of Rennes and Geoffrey Berengar, was the eldest son of Duke Conan I of Brittany. He was Count of Rennes, by right of succession. In 992 he assumed the title of Duke of Brittany, which had long been an independent state, but he had little control over much of Lower Brittany.
Odo of Rennes, Count of Penthièvre, was the youngest of the three sons of Duke Geoffrey I of Brittany and Hawise of Normandy, daughter of Richard I of Normandy. Eudon married Agnes of Cornouaille, the daughter of Alan Canhiart, Count of Cornouaille and sister of Hoel II, Duke of Brittany who was married in 1066 to Eudon's niece Hawise, Duchess of Brittany.
Alan III of Rennes was Count of Rennes and duke of Brittany, by right of succession from 1008 to his death.
Conan II of Rennes was Duke of Brittany, from 1040 to his death. Conan was the eldest child and heir of Alan III, Duke of Brittany by his wife Bertha of Blois, and member of the House of Rennes. He was the elder brother of Hawise, who succeeded him as suo jure duchess.
Hoël II was Count of Kernev, from 1058 as Hoël V. On the basis of his marriage to Hawise, Duchess of Brittany, in 1066, he became Duke of Brittany jure uxoris.
Conan III, also known as Conan of Cornouaille and Conan the Fat was duke of Brittany, from 1112 to his death. He was the son of Alan IV, Duke of Brittany and Ermengarde of Anjou.
Odo II, Count of Porhoet was the son of Geoffroy, Viscount de Porhoët, and his wife Hawise. He became Duke of Brittany in 1148, jure uxoris, upon his marriage to Bertha, Duchess of Brittany.
Conan IV, called the Young, was the Duke of Brittany from 1156 to 1166. He was the son of Bertha, Duchess of Brittany, and her first husband, Alan, Earl of Richmond. Conan IV was his father's heir as Earl of Richmond and his mother's heir as Duke of Brittany. Conan and his daughter Constance would be the only representatives of the House of Penthièvre to rule Brittany.
Conan I nicknamed Le Tort was the Duke of Brittany from 990 to his death.
Alan, 1st Earl of Richmond, Breton Alan Penteur, also known as "Alan the Black", was a Breton noble who fought for Stephen, King of England. Alan was the third son of Stephen, Count of Tréguier, and Hawise de Guingamp.
Stephen of Penthièvre, Count of Tréguier, 3rd Lord of Richmond was a Breton noble and a younger son of Odo, Count of Penthièvre and Agnes of Cornouaille, sister of Hoël II, Duke of Brittany. In 1093, he succeeded to the title of Count of Tréguier; in 1098, he succeeded his brother Alain as Lord of Richmond in Yorkshire, England.
The counts of Nantes were originally the Frankish rulers of the Nantais under the Carolingians and eventually a capital city of the Duchy of Brittany. Their county served as a march against the Bretons of the Vannetais. Carolingian rulers would sometimes attack Brittany through the region of the Vannetais, making Nantes a strategic asset. In the mid-ninth century, the county finally fell to the Bretons and the title became a subsidiary title of the Breton rulers. The control of the title by the Breton dukes figured prominently in the history of the duchy. The County of Nantes was given to Hoel, a disinherited son of a duke. He lost the countship due to a popular uprising. That uprising presented an opportunity for King Henry II of England to attack the Breton duke. In the treaty ending their conflicts, the Breton duke awarded the county to Henry II.
Judith of Rennes (982–1017), was Duchess of Normandy from c. 1000 until her death.
Hawise of Rennes was sovereign Duchess of Brittany from 1066 until her death.
Bertha of Cornouaille, also known as Bertha of Brittany, was the Duchess of Brittany between 1148 until her death and Dowager Countess of Richmond. Bertha was the elder daughter of Conan III of Brittany by Maude, the illegitimate daughter of King Henry I of England. She was the last member of the Breton House of Cornouaille to reign over Brittany.
Ermengarde of Anjou, also known as Ermengarde of Brittany, was a member of the comital House of Anjou and by her two marriages was successively Duchess of Aquitaine and Brittany. She was also a patron of Fontevraud Abbey. Ermengarde was the regent of Brittany during the absence of her spouse, Duke Alan IV of Brittany, from 1096 until 1101.
The Count of Rennes was originally the ruler of the Romano-Frankish civitas of Rennes. From the middle of the ninth century these counts were Bretons with close ties to the Duchy of Brittany, which they often vied to rule. From 990 the Counts of Rennes were usually Dukes of Brittany. In 1203 the county was integrated into the ducal demesne. The Count of Rennes was a title held by the House of Rennes.
Matthew II was the Count of Nantes from 1084 until his death. He was the second son of Duke Hoël II of Brittany and Hawise. He was named for his father's cousin, Count Matthew I of Nantes, perhaps on the presumption that he would inherit Nantes.
Guerech of Brittany, was Count of Nantes and Duke of Brittany from 981 to 988.