Robert, Earl of Essex, the son of Walter Devereux, Viscount Hereford, was born at Netherwood, in Herefordshire, November 10, 1567. He succeeded to the title of Earl of Essex at the age of ten; and about two years afterwards was sent by his guardian, Lord Burghley, to Trinity College, Cambridge. He took the degree of master of arts in 1582, and soon afterwards retired to his seat at Lampsie, in South Wales. He did not, however, continue long in this retreat; for we find him, in his seventeenth year, at the court of Queen Elizabeth, by whom he was immediately honoured with singular marks of favour. Authors seem very unnecessarily perplexed to account for this young earl's gracious reception at the court of Elizabeth. But the reasons seem pretty obvious; he was her relation, the son of one of her most faithful servants, the son-in-law of her favourite Leicester, and a very handsome and accomplished youth. Towards the end of 1585, he attended the Earl of Leicester to Holland; and gave signal proofs of his personal courage during the campaign of 1586, particularly at the battle of Zutphen, where the gallant Sir Philip Sidney was mortally wounded. On this occasion the Earl of Leicester conferred on Essex the honour of knight banneret.

In 1587, on Leicester's being appointed lord steward of the household, Essex succeeded him in the honourable post of master of the horse; and the year following, when the queen assembled an army at Tilbury to oppose the Spanish invasion, Essex was made general of the horse. From this time he was considered as the favourite of the queen; and if any mark was yet wanting to fix the opinion of the people in this respect, it was shown by the queen's conferring on him the honour of the garter.

It is not to be wondered at that so rapid an elevation should have affected the mind of the youthful earl, who henceforward showed a very high spirit, and often behaved haughtily to the queen herself. His eagerness about this time to dispute her favour with Sir Charles Blount, afterwards Lord Mountjoy and Earl of Devonshire, cost him some blood; for Sir Charles, thinking himself affronted by the earl, challenged him, and after a short contest wounded Essex in the knee. The queen, so far from being displeased with this occurrence, is said to have sworn a good round oath that it was fit somebody should take him down, otherwise there would be no ruling him. However, she reconciled the rivals, who, to their credit, continued good friends as long as they lived.

The gallant Essex, however, was not so entirely captivated with his situation as to become insensible to the allurements of military glory. In 1589, Sir John Norris and Sir Francis Drake having sailed on an expedition against Spain, the young favourite, without the permission or knowledge of his royal mistress, followed the fleet, which he joined as they were sailing towards Lisbon, and acted with great resolution in the repulse of the Spanish garrison of that city. The queen wrote him a very severe letter on the occasion; but, after his return, she was soon appeased. Yet it was not long before he again incurred her displeasure, by marrying the widow of Sir Philip Sidney. In 1591 he was sent to France with the command of 4000 men to the assistance of Henry IV. In 1596 he was joined with the lord high admiral Howard in the command of the famous expedition against Cadiz, the success of which is universally known. In 1597 he was appointed master of the ordnance, and the same year commanded another expedition against Spain, called the Island Voyage.

Soon after his return he was created earl marshal of England; and, on the death of the great Lord Burghley in 1598, elected chancellor of the university of Cambridge. This, however, may be regarded as the turning-point of his fortunes. His enemies, who had long looked with jealousy on his honours, now conspired together to effect his downfall. The first shock he received in the queen's favour arose from a warm dispute in regard to the nomination of a viceroy for Ireland. The affair is related by Camden, who tells us that nobody was present except the lord admiral, Sir Robert Cecil, secretary, and Windebank, clerk of the seal. The queen wished Sir William Knolls, uncle of Essex, to be named as her representative; but Essex pressed the appointment of Sir George Carew. Unable to persuade the queen to approve his choice, Essex so far forgot his duty as to turn his back upon her in a contemptuous manner; and her Majesty resented the insolence by giving him a box on the ear, and bidding him go and be hanged. On this the earl put his hand to his sword and swore revenge. This violent storm, however, soon subsided, and they were again, to all appearance, reconciled.

A more disastrous result, however, followed his fatal pre-ferment to the lord-lieutenancy of Ireland in the same year. For this appointment he was more indebted to the malice of his enemies than the confidence of his friends. In the midst of the disasters which attended his first efforts for the reduction of Ireland, an army was suddenly raised in England under the command of the Earl of Nottingham, on the pretext that Essex meditated an invasion of his native country, rather than the reduction of the Irish rebels. To justify his conduct and repel this insinuation, Essex quitted his post and came over to England without leave. On his arrival he burst into her Majesty's bed-chamber as she was rising, and was received with a mixture of tenderness and severity; but she soon afterwards deprived him of all his appointments except that of master of the horse; and he was committed to the custody of the lord-keeper, with whom he continued six months. No sooner had he regained his liberty than he plunged into the most reckless extravagancies, consulting nothing but the dictates of his own powerful passions. He first determined to obtain an audience of the queen by force; and afterwards refused to attend the council when summoned. When the queen sent the lord-keeper, the lord chief-justice, and two others, to learn his grievances, he confined them, and then marched with his friends into the city, in expectation that the people would rise in his favour. But in this he was completely disappointed. He was at last besieged and taken in his house in Essex Street; and after being committed to the Tower, he was tried, condemned, and executed February 25, 1601.

The queen was long irresolute in the signing of the warrant for his execution, and doubtless had he appealed to her clemency, he would have been pardoned. Essex was an accomplished scholar, and a generous patron of literature. He perished in the thirty-fourth year of his age, leaving one son and two daughters.