Edmund Mortimer was the second son of Edmund Mortimer, 3rd Earl of March by his wife Philippa Plantagenet

Philippa Plantagenet, 5th Countess of Ulster

Philippa of Clarence was the Countess of Ulster suo jure.Philippa was born in Eltham Palace, Kent, England on 16 August 1355. She was the daughter and only child of Lionel of Antwerp, 1st Duke of Clarence and Elizabeth de Burgh, 4th Countess of Ulster...

, and is the best-known of the various Edmund Mortimers because of his role in the rebellion of Owain Glyndŵr

Owain Glyndwr

Owain Glyndŵr , or Owain Glyn Dŵr, anglicised by William Shakespeare as Owen Glendower , was a Welsh ruler and the last native Welshman to hold the title Prince of Wales...

. A grandson of Lionel of Antwerp and thus descended from King Edward III of England

Edward III of England

Edward III was King of England from 1327 until his death and is noted for his military success. Restoring royal authority after the disastrous reign of his father, Edward II, Edward III went on to transform the Kingdom of England into one of the most formidable military powers in Europe...

, he was born at Ludlow Castle

Ludlow Castle

Ludlow Castle is a large, partly ruined, non-inhabited castle which dominates the town of Ludlow in Shropshire, England. It stands on a high point overlooking the River Teme...

 in Shropshire

Shropshire

Shropshire is a county in the West Midlands region of England. For Eurostat purposes, the county is a NUTS 3 region and is one of four counties or unitary districts that comprise the "Shropshire and Staffordshire" NUTS 2 region. It borders Wales to the west...

.

Claim to throne

Edmund was a supporter of his first cousin once removed, Henry Bolingbroke

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...

, despite having at least as good a claim to the throne of England. (Edmund's grandfather, Lionel of Antwerp, 1st Duke of Clarence

Lionel of Antwerp, 1st Duke of Clarence

Lionel of Antwerp, 1st Duke of Clarence, jure uxoris 4th Earl of Ulster and 5th Baron of Connaught, KG was the third son, but the second son to survive infancy, of Edward III of England and Philippa of Hainault...

, was Edward III's third son, while Bolingbroke's father (John of Gaunt) was Edward's fourth son.)

Capture by Owain Glyndŵr

Edmund fought for Bolingbroke until captured by the Welsh

Welsh people

The Welsh people are an ethnic group and nation associated with Wales and the Welsh language.John Davies argues that the origin of the "Welsh nation" can be traced to the late 4th and early 5th centuries, following the Roman departure from Britain, although Brythonic Celtic languages seem to have...

 rebel leader, Owain Glyndŵr

Owain Glyndwr

Owain Glyndŵr , or Owain Glyn Dŵr, anglicised by William Shakespeare as Owen Glendower , was a Welsh ruler and the last native Welshman to hold the title Prince of Wales...

 in the Battle of Bryn Glas

Battle of Bryn Glas

The Battle of Bryn Glas, was fought on 22 June 1402, near the towns of Knighton and Presteigne in Powys...

.

When Henry proved 'slow' to ransom Mortimer, Glyndŵr won Edmund Mortimer's allegiance. Mortimer married Glyndŵr's daughter Catrin

Catrin ferch Owain Glyndwr

Catrin ferch Owain Glyndŵr was one of the daughters of Margaret Hanmer and Owain Glyndŵr.- Lineage :Glyndŵr, a prince of the old Welsh royal house of Powys Fadog of the Mathrafal line, led a major revolt in Wales between 1400 and c.1416, taking the title of "Prince of Wales".Little is known about...

 in 1402, and they are believed to have had at least 3 children in their six years together. Some sources indicate that Catrin and "3 daughters" died during imprisonment in the Tower of London in 1413.

Tripartite Indenture

Glyndŵr and Mortimer plotted with Henry Percy, nicknamed Hotspur, to depose Henry IV and divide the kingdom of England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 and Wales

Wales

Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

 in three. However, Mortimer died sometime during the eight month siege of Owain's stronghold of Harlech

Harlech

Harlech is a town and seaside resort in Gwynedd, within the historical boundaries of Merionethshire in northwest Wales. Lying on Tremadog Bay and within the Snowdonia National Park, it has a population of 1,952, of whom 59% speak Welsh...

, in 1409, by Henry, Prince of Wales

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....

. Mortimer most likely died of plague

Bubonic plague

Plague is a deadly infectious disease that is caused by the enterobacteria Yersinia pestis, named after the French-Swiss bacteriologist Alexandre Yersin. Primarily carried by rodents and spread to humans via fleas, the disease is notorious throughout history, due to the unrivaled scale of death...

or starvation.