Walter Devereux is the eldest son of Sir Richard Devereux and the grandson of Walter Devereux, Viscount Hereford, to whose title he had succeeded in 1558.

He had married Lettice, daughter of Sir Francis Knollys, sometime between 1560 and 1565.

Having served in the suppression of the Northern Rebellion in 1569, he had in 1572 been created 1st earl of Essex.

Essex offers in the spring of 1573  to subdue and colonize, at his own expense, that portion of Ulster which has not accepted English overlordship, the region that is dominated by the rebellious O'Neills, led by Sir Brian MacPhelim and Turlough Luineach O'Neill, and supported by the Scots-Irish under Sorley Boy MacDonnell.

Drake returns to Plymouth on August 9, 1573, with a mere thirty Englishmen, every one of them rich for life.

Unfortunately, his return coincides with a moment when Elizabeth and Philip have reached a temporary truce.

Elizabeth, who has up to this point sponsored and encouraged Drake's raids, cannot officially acknowledge piracy, although she is delighted with Drake's success in the empire of her great enemy.

Drake, seeing that the time is inauspicious, ...

...sails with a small squadron to Ireland, where he serves under the earl of Essex.

Essex, arriving in Ireland by autumn 1573, is soon engaged in intrigues to divide his enemies, and he has difficulty obtaining the continued cooperation of Queen Elizabeth and her lord deputy of Ireland, Sir William Fitzwilliam.

Sorley Boy has spent the past few years in striving to frustrate the schemes of Smith, and now those of Essex, for colonizing Ulster with English settlers.

He is willing to come to terms with the government provided his claims to the lands are allowed, but Essex determines to reduce him to unconditional submission.

After a retreat into Scotland, Sorley Boy had returned and made an unsuccessful attempt on the crown garrison at Carrickfergus.

He had eventually come to terms with Smith, who supports his claims to title in the Route on condition that he take up the reformed religion.

Letters of denization had been addressed to Sorley Boy from the crown in 1573, but Essex has frustrated these with the renewal of his plantation scheme; still, Sorley Boy manages to hold his position, when Essex fails in his negotiation with the Scottish regent and the Earl of Argyll of a withdrawal of the Scots from Ulster.

Essex’s military operations have meanwhile taken the form of raids characterized by brutal massacres of the populace.

After capturing Brian MacPhelim, through treachery, in October 1574 at a conference in Belfast, ...

...Essex has MacPhelim and his wife and half brother, all of whom are his guests, executed at Dublin.

Turlough Luineach O'Neill, chief of Tyrone, successor to his cousin Shane O'Neill, had made professions of loyalty to Elizabeth I of England, seeking to strengthen his position by alliance with the O'Donnells, MacDonnells, and MacQuillans.

When his conduct gives rise to suspicions, an expedition under the Earl of Essex is sent against him, which meets with such doubtful success that in 1575 a treaty is arranged by which Turlough receives extensive grants of lands and permission to employ three hundred Scottish mercenaries.

Elizabeth, on advice from Leicester, commands Essex to “break off his enterprise” in 1575.

Essex now switches tack, having struck a deal with Turlough Luineach O'Neill, and defeats Sorley Boy around Castle Toome, where the Bann flows out of Lough Neagh.

Essex has to withdraw to Carrickfergus for lack of provisions, but he now orders a follow-up operation, with the intention of driving the Scots from Ulster.

Under the commands of John Norreys and Francis Drake, an amphibious strike force of eleven hundred and fifty men in three frigates proceeds by sea from Carrickfergus to ...

...Rathlin Island, where Sorley Boy's children and valuables, together with the families of his principal retainers, have been lodged in the caves for safety.

Drake is in charge of the ships which transport Norreys' troops to Rathlin, commanding a small frigate called Falcon, with a total complement of twenty-five; he is charged with the task of keeping Scottish vessels from bringing reinforcements to the island.

While the chieftain is himself at Ballycastle, within sight of the island, the English break the defenses of the castle, where the retainers have fled, after a four-day siege, and massacre the six or seven hundred women, children, and old men.

A fort is erected on the island, but is evacuated by Norreys, and he is recalled with his troops to Dublin within three months, when it becomes clear that the plantation effort will fail.

Elizabeth bestows on Essex a barony in Monaghan and the office of earl marshal of Ireland to compensate him for his losses here.