Administration and government
At its largest extent, the Angevin Empire consisted of the Kingdom of England, the Lordship of Ireland, the Duchies of Normandy (which included the Channel Islands), Gascony and Aquitaine as well as of the Counties of Anjou, Poitou, Maine, Touraine, Saintonge, La Marche, Périgord, Limousin, Nantes and Quercy.
While the Duchies and Counties were held with various levels of vassalage to the king of France, the Plantagenets held various levels of control over the Duchies of Brittany and Cornwall, the Welsh princedoms, the county of Toulouse, and the Kingdom of Scotland, although those regions were not formal parts of the empire.
Auvergne was also in the empire for part of the reigns of Henry II and Richard, in their capacity as Dukes of Aquitaine. Henry II and Richard I pushed further claims over the County of Berry but these were not completely fulfilled and the county was lost completely by the time of the accession of John in 1199.

The frontiers of the empire were sometimes well known and therefore easy to mark, such as the dykes constructed between the royal demesne of the King of France and the Duchy of Normandy. In other places these borders were not so clear, particularly the eastern border of Aquitaine, where there was often a difference between the frontier Henry II, and later Richard I, claimed, and the frontier where their effective power ended.
Scotland was an independent kingdom, but after a disastrous campaign led by King William I the Lion, English garrisons were established in the castles of Edinburgh, Roxburgh, Jedburgh and Berwick in southern Scotland as defined in the Treaty of Falaise.
Administration and government
One characteristic of the Angevin Empire was its “polycratic” nature, a term taken from a political pamphlet written by a subject of the Angevin Empire: the Policraticus by John of Salisbury. This meant that, rather than the empire being controlled fully by the ruling monarch, he would delegate power to specially appointed subjects in different areas.
Britain
England was under the firmest control of all the lands in the Angevin Empire, due to the age of many of the offices that governed the country and the traditions and customs that were in place. England was divided in shires with sheriffs in each enforcing the common law. A justiciar was appointed by the king to stand in his absence when he was on the continent. As the kings of England were more often in France than England they used writs more frequently than the Anglo-Saxon kings, which actually proved beneficial to England.
Under William I’s rule, Anglo-Saxon nobles had been largely replaced by Anglo-Norman ones who couldn’t own large expanses of contiguous lands, because their lands were split between England and France. This made it much harder for them to revolt against the king and defend all of their lands at once. Earls held a status similar to that of the continental counts, but there were no dukes at this time, only ducal titles that the kings of England held.
The Principality of Wales obtained good terms provided it paid homage to the Plantagenets and recognised them as lords. However, it remained almost self-ruling. It supplied the Plantagenets with infantry and longbowmen.
Ireland
Ireland was ruled by the Lord of Ireland who had a hard time imposing his rule at first. Dublin and Leinster were Angevin strongholds while Cork, Limerick and parts of eastern Ulster were taken by Anglo-Norman nobles.
The Lordship of Ireland sometimes referred to retroactively as Norman Ireland, was the part of Ireland ruled by the King of England (styled as “Lord of Ireland”) and controlled by loyal Anglo-Norman lords between 1177 and 1542. The lordship was created following the Norman invasion of Ireland in 1169–1171. It was a papal fief, granted to the Plantagenet kings of England by the Holy See, via Laudabiliter. As the lord of Ireland was also the king of England, he was represented locally by a governor, variously known as justiciar, lieutenant, or lord deputy.

France
France in 1180. The Angevin kings of England held all the red territories.
All the continental domains that the Angevin kings ruled were governed by a seneschal at the top of the hierarchical system, with lesser government officials such as baillis, vicomtes, and prévôts. However, all counties and duchies would differ to an extent.
Greater Anjou is a modern term to describe the area consisting of Anjou, Maine, Touraine, Vendôme, and Saintonge. Here, prévôts, the seneschal of Anjou, and other seneschals governed. They were based at Tours, Chinon, Baugé, Beaufort, Brissac, Angers, Saumur, Loudun, Loches, Langeais and Montbazon.
However, the constituent counties, such as Maine, were often administered by the officials of the local lords, rather than their Angevin suzerains. Maine was at first largely self-ruling and lacked administration until the Angevin kings made efforts to improve administration by installing new officials, such as the seneschal of Le Mans. These reforms came too late for the Angevins however, and only the Capetians saw the beneficial effects of this reform after they annexed the area.
Aquitaine differed in the level of administration in its different constituent regions. Gascony was a very loosely administrated region. Officials were stationed mostly in Entre-Deux-Mers, Bayonne, Dax, but some were found on the pilgrimage route to Santiago de Compostela and also on the river Garonne up to Agen. The rest of Gascony was not administered, despite being such a large area compared to other smaller, well-administered provinces.
This difficulty when it came to administering the region wasn’t new – it had been just as difficult for the previous Poitevin dukes to cement their authority over this area. A similar state of affairs was found in the eastern provinces of Périgord and Limousin, where there was not much of a royal administrative system and practically no officials were stationed. Indeed, there were lords that ruled these regions as if they were “sovereign princes” and they had extra powers, such as the ability to mint their own coins, something English lords had been unable to do for decades.
These officials were introduced during the 12th century in Normandy and cause an organisation of the duchy similar to the sheriffs in England. Ducal authority was the strongest on the frontier near the Capetian royal demesne.
Toulouse was held through weak vassalage by the Count of Toulouse but it was rare for him to comply with Angevin rule. Only Quercy was directly administrated by the Angevins after Henry II’s conquest in 1159, but it did remain a contested area.
Brittany, a region where nobles were traditionally very independent, was under Angevin control during Henry II and Richard I’s reigns. The county of Nantes was under the firmest control. The Angevins often involved themselves in Breton affairs, such as when Henry II installed the archbishop of Dol and arranged Duke Conan IV of Brittany’s marriage to Margaret of Huntingdon (1144/45 – 1201).
Here is some family background on Margaret that you may find interesting. Margaret was a Scottish princess, the daughter of Henry of Scotland, Earl of Huntingdon and Northumbria, and Ada de Warenne. She was the sister of Scottish kings Malcolm IV and William I.
Margaret’s father, Henry of Scotland (1114 — 1152), was heir apparent to the Kingdom of Alba. He was also the 3rd Earl of Northumberland and the 3rd Earl of Huntingdon. He was the son of King David I of Scotland and Queen Maud, 2nd Countess of Huntingdon.
Margaret’s mother, Maud was the daughter of Waltheof, the Anglo-Saxon Earl of Huntingdon and Northampton, and his French wife Judith of Lens. Her father was the last of the major Anglo-Saxon earls to remain powerful after the Norman conquest of England in 1066, and the son of Siward, Earl of Northumbria. Her mother was the niece of William the Conqueror, which makes Maud his grand-niece. Through her ancestors the Counts of Boulogne, she was also a descendant of Alfred the Great and Charles the Bald and a cousin of Godfrey of Bouillon.
Margaret’s second husband was Humphrey de Bohun, hereditary Constable of England. Following her second marriage, Margaret styled herself as the Countess of Hereford.