Robert de Vere was the 9th Earl of Oxford, he became the first Marquess of Dublin in 1385 and the first Duke of Ireland in 1386.

He was a favourite court companion to Richard II and was considered by his rivals at court to be more than a companion.

Close Roll, 12 Richard II

Item no. 3

20 March 1389

 To the mayor and bailiffs of Dublin.  On 22nd June [1383] 7 Richard II, the King granted to John Bernolby the custody of his castle of Dublin with the officers of gaoler and janitor, and all fees and profits to hold for life; and afterwards he granted to Robert [de Vere], marquis of Dublin, the lordship of Ireland with all offices in that land, notwithstanding any grants made by the King before that time. And on 14th March [1386] following, at the supplication of the said John, the King ratified the said letters of custody notwithstanding the grant to the marquis. ORDER to pay any fees to John that may be in arrears.

Authorised:  By petition endorsed by the justiciar and council, and sealed with the privy seal.

From the Patent Rolls of Richard II, no 9, 18th of September 1386.

MEMORANDUM¹ that on 30 Aug. [1386] in the present year, the noble John Stanley, Lt of Robert [de Vere] marquis of Dublin, landed at Dalkey in the afternoon. On 1 Sept., he arrived at Dublin and, on 18 Sept., letters patent made to the Lt and sealed under the g.s. of the said lord marquis were displayed and read out in the great chamber [magna camera] of Dublin castle in the presence of the venerable father Alexander [Balscot], bp Meath, C. of the lord marquis in Ire.; Robert Crull clk, T. of the lord marquis there; brother Thomas Scurlag, abbot of St Thomas the Martyr near Dublin; Maurice fitz Thomas, e. Kildare; Edmund del Clay, chief justice of the chief place, and John Tyrell, chief justice of the common bench of the said marquis in that land; and others. The tenor of those letters was as follows:

Patent Roll, 10 Richard II

Item no. 270

Kilkenny 16th May 1387

The King granted to Robert [de Vere] marquis of Dublin his land and lordship of Ireland to have for life. The marquis wishes to provide for the good governance, salvation and defence of that land and the faithful lieges of the same, as he is obliged to do. Trusting in the fealty, wisdom and circumspection of Philip son of William Barry, ORDER firmly enjoining him to labour both for the maintenance of the King's peace in County Cork and upon the punishment of all malefactors in that county, both Irish and English, APPOINTMENT by the marquis of Philip son of William Barry as keeper of the peace in County Cork.

Robert's rivals formed an opposition to him which became known as the, Lords Appellant.

According to the 16th-century chronicler Raphael Hollinshed

In 1387, King Richard II sent secretly to Robert de Vere, Duke of Ireland, who was levying troops in Wales, to come to him with all speed.

De Vere in oppostion to this group led the forces of Richard II to defeat at the Battle of Radcot bridge, having lost the field De Vere fled abroad into exile.

The merciless Parliament of 1388 attainted him and sentenced him to death, he forfeit his title and lands.

The administration of Ireland  which comprised, John Stanley, his deputy, James Butler, Earl of Ormond, Alexander, Bishop of Meath and Sir Robert Crull, treasurer were all dismissed. They were later reinstated.

The merciless parliament sat for three months from the beginning of February through to the beginning of June, as Edmund was ordered to be arrested in April, he was probaly no longer considered a member of the administration.

De Vere died in exile in 1392.