The House of Lancaster was a branch of the royal House of Plantagenet

House of Plantagenet

The House of Plantagenet , a branch of the Angevins, was a royal house founded by Geoffrey V of Anjou, father of Henry II of England. Plantagenet kings first ruled the Kingdom of England in the 12th century. Their paternal ancestors originated in the French province of Gâtinais and gained the...

. It was one of the opposing factions involved in the Wars of the Roses

Wars of the Roses

The Wars of the Roses were a series of dynastic civil wars for the throne of England fought between supporters of two rival branches of the royal House of Plantagenet: the houses of Lancaster and York...

, an intermittent civil war

Civil war

A civil war is a war between organized groups within the same nation state or republic, or, less commonly, between two countries created from a formerly-united nation state....

 which affected England and Wales

England and Wales

England and Wales is a jurisdiction within the United Kingdom. It consists of England and Wales, two of the four countries of the United Kingdom...

 during the 15th century. The family provided England with three kings: Henry IV of England

Henry IV of England

Henry IV was King of England and Lord of Ireland . He was the ninth King of England of the House of Plantagenet and also asserted his grandfather's claim to the title King of France. He was born at Bolingbroke Castle in Lincolnshire, hence his other name, Henry Bolingbroke...

, who ruled 1399–1413; Henry V of England

Henry V of England

Henry V was King of England from 1413 until his death at the age of 35 in 1422. He was the second monarch belonging to the House of Lancaster....

, who ruled 1413–1422; and Henry VI of England

Henry VI of England

Henry VI was King of England from 1422 to 1461 and again from 1470 to 1471, and disputed King of France from 1422 to 1453. Until 1437, his realm was governed by regents. Contemporaneous accounts described him as peaceful and pious, not suited for the violent dynastic civil wars, known as the Wars...

 and (II of) France

Dual monarchy of England and France

The dual monarchy of England and France existed during the latter phase of the Hundred Years' War when Charles VII of France and Henry VI of England disputed the succession to the throne of France...

, who ruled 1422–1461 and 1470–1471.
The House descended from Edward III's third surviving son, John of Gaunt

John of Gaunt, 1st Duke of Lancaster

John of Gaunt, 1st Duke of Lancaster , KG was a member of the House of Plantagenet, the third surviving son of King Edward III of England and Philippa of Hainault...

. Gaunt did not receive a large inheritance, so he made his fortune through marriage to the heiress Blanche of Lancaster

Blanche of Lancaster

Blanche of Lancaster, Duchess of Lancaster was an English noblewoman and heiress, daughter of England's wealthiest and most powerful peer, Henry of Grosmont, 1st Duke of Lancaster...

, who brought with her the considerable lands of the Earls of Leicester

Earl of Leicester

The title Earl of Leicester was created in the 12th century in the Peerage of England , and is currently a title in the Peerage of the United Kingdom, created in 1837.-Early creations:...

 and Lancaster

Earl of Lancaster

The title of Earl of Lancaster was created in the Peerage of England in 1267, merging in the crown in 1399. See also Duke of Lancaster.-Earls of Lancaster :...

, which made Gaunt the wealthiest landowner in England after the King.