Capel, Arthur (1631–83), earl of Essex and lord lieutenant of Ireland, was baptised 28 January 1631, the eldest son and heir among three sons and four daughters of Arthur Capel, 1st Baron Capel of Hadham, Hertfordshire, and his wife, Elizabeth (née Morrison) of Cassiobury Park, Hertfordshire. He was largely self-educated and his early life remains obscure, but he may have fought as a royalist during the English civil war. He succeeded as 2nd Baron Capel on 9 March 1649, after his father's execution as a royalist. After the restoration he was appointed lord lieutenant of Hertfordshire (1660–81), and on 20 April 1661 was created Viscount Malden and earl of Essex, partly in recognition of his father's loyalty. Subsequently lord lieutenant of Wiltshire (1668–72), he was appointed as ambassador to Denmark (1669) and a member of the English privy council (17 April 1672–24 January 1681).
Essex was appointed lord lieutenant of Ireland on 21 May 1672 in succession to Lord Berkeley (qv). Sworn in on 5 August 1672, he was apparently surprised at his appointment, ‘for he had not pretended to it: and he was a violent enemy to popery’ (Burnet, History, ii, 108); certainly Archbishop Oliver Plunkett (qv) was initially deeply concerned about Essex's possible attitude towards catholics. Religious policy was fundamental to Essex's instructions, which largely echoed those of his predecessors. Remonstrant clergy were to be supported, provincial presidencies were to be suppressed, and a general reform of the civil and military establishments initiated; Essex immediately ordered a restructuring of the army on his arrival. But his private instructions from the king allowed him the discretion to apply the oaths of allegiance and supremacy as he saw fit, to ensure catholic appointments to commissions of the peace, to determine an appropriate policy for religious toleration, and, crucially, to come to some accommodation with the catholic clergy.
Assiduous, diligent, and capable, Essex rapidly mastered his brief. Yet, while religious policy was his initial priority, he rapidly identified finance as a key issue. Ordered to support the revenue undertaking of Richard Jones (qv), earl of Ranelagh, he was to scrutinise the accounts and guarantee the payments. Essex had a measure of independence that he was loath to relinquish; the integrity of his authority was a constant preoccupation. He successfully blocked (1673) a grant of the Phoenix Park to the duchess of Cleveland, Charles II's mistress, as it might set a dangerous precedent for undermining viceregal authority; he sought to deal with the aftermath of Berkeley's disastrous intervention in Dublin corporation on similar grounds. He suppressed the provincial presidencies as ordered, though limited military powers were initially retained by the lord president of Munster, Roger Boyle (qv), earl of Orrery. These were later removed; Essex proved unwilling to be influenced by sectional interests in formulating security policy. Orrery may have sought to undermine (and supplant) Essex, whose tenure coincided with concerns about Ireland in the English parliament.
From October 1673 proclamations were issued ordering the disarming of catholics and their expulsion from civic offices, the banishment of catholic clergy and the suppression of catholic institutions. Essex was not assiduous on all of these points; the proclamations were not stringently enforced. Yet, while he was inclined towards toleration, his hand was forced by parliamentary pressure from England; he was expected to encourage the protestant interest while suppressing catholicism (though it was noted that as the proclamation banishing clergy had mainly affected remonstrants, allowance should have been made for this). Essex initially favoured the jurisdictional claims of Archbishop Peter Talbot (qv) over Plunkett. However, in May 1673 Essex sought the dismissal of his chief secretary, Sir Henry Ford (qv), for passing information to Talbot. Plunkett enjoyed good relations with Essex, attributing this to his inclination to avoid politics, but Essex held him in high regard. Plunkett's assistance in dealing with the persistent problem of tories also proved useful, but he remained wary of provoking further persecution; Essex, up to a point, was dominated by external pressures. Yet while continually concerned about presbyterian activity in Ulster, Essex resisted demands from the anglican episcopate for harsher measures and took a moderate line towards dissenters, albeit largely on security grounds.
As from March 1673 complaints were emerging about Ranelagh's excesses, Essex proved more critical of Ranelagh himself than the actual undertaking, the efficiency of which he readily conceded. His protestant reputation guaranteed him a strong position at this time, though he remained wary of Ranelagh, especially given the latter's closeness to the earl of Danby. But in the absence of potential replacements, Essex could put pressure on Ranelagh; the continual swindling of military finances, especially in times of crisis, proved a running sore. But in July 1674 his financial authority was curtailed, and by August Essex was aware that viceregal authority was being increasingly reserved to London. However, he enjoyed good relations with James Butler (qv), duke of Ormond, following Ormond's policy of fostering division among the Catholic clergy. While Ormond exerted influence in parliament on Essex's behalf, Essex in turn often deferred to Ormond's wishes. However, from February 1675 Essex was openly advocating the calling of an Irish parliament, stating his opposition to the existing revenue farm in April, and arguing that parliament was the most appropriate means of dealing with the revenue.
In 1675 Essex went to England (25 June–5 July); Archbishop Michael Boyle (qv) and Sir Arthur Forbes (qv) served as lords justices in his absence. Essex retained royal favour despite numerous enemies at court, being strongly supported by his secretary, Sir William Harbord (qv), but in June 1675 he decisively broke with Ranelagh, and by September had been effectively stripped of fiscal responsibility; in this respect, the independence of his government was largely undermined. He had been aware of continual rumours of his recall and imminent replacement by a number of prominent figures, but his recall was seemingly inevitable by May 1676. Ormond sought and obtained the post, but continued to support Essex, whose unhappiness at Ranelagh's conduct saw him attempt to curb the activities of the revenue farmers. From August 1676 Essex had been demanding their accounts. Highly critical of their conduct in February 1677, in March he refused to pass Ranelagh's accounts. However, his constant inquiries had irritated the king, and Ranelagh now pressed for a more congenial replacement. However, Ormond had extracted from Charles a promise of reappointment, and was duly appointed lord lieutenant on 24 May 1677. Essex had anticipated his dismissal, and as a mark of respect to Ormond, declined to appoint lords justices, handing over the sword personally on 24 August 1677.
Essex's subsequent dealings with Ireland were largely indirect. He pledged his support to Ormond in Irish matters in October 1677, but during the exclusion crisis he became a leading figure in the nascent whig opposition. Apparently intent on reappointment as viceroy, he became markedly hostile to Ormond; in early 1679 he was seen as a strong contender to replace Ormond, but was instead appointed first lord of the treasury (March–November 1679). He was by now aligned with the earl of Shaftesbury, whose promotion of an ‘Irish plot’ sought to bolster the campaign to exclude James (qv), duke of York, from the succession, and at least one anti-Irish tract was specifically addressed to Essex at this time. He supported the Irish revenue proposals (1679–80) of Sir James Shaen (qv), but his hostility to Ormond was such that in January 1681 Richard Butler (qv), earl of Arran, threatened to investigate alleged misdemeanours in Essex's own viceregal government. In June 1681 Essex and Shaftesbury supported the claims of the informer James Carroll for the existence of an ‘Irish plot’ since 1672. However, Essex unsuccessfully argued for Oliver Plunkett's innocence prior to Plunkett's execution in July 1681. Later accused of involvement in the Rye House plot, Essex was imprisoned in the Tower of London (June 1683). He was found dead there on 13 July 1683, having apparently cut his own throat. Fruitless controversy ensued as to whether this was murder or suicide.
He married (19 May 1653) Elizabeth (d. 1718), daughter of Algernon Percy, earl of Northumberland. Of six sons only one, Algernon, survived to adulthood, and succeeded to the earldom. Essex's younger brother, Sir Henry Capel (qv), later served in Ireland as lord deputy (1695–6). An extensive collection of Essex's Irish papers is retained in the BL (Stowe MSS 200–17). Selections have been published: Letters written by his excellency Arthur Capel, earl of Essex, in the year 1675 (London, 1770), and a broader selection as Essex papers, ed. Osmund Airy and C. E. Pike (2 vols, Camden Society, 1890–1913). Three extant portraits of Essex by Sir Peter Lely survive: in Badminton House, Avon; the Yale Centre for British Art; and Syon House, Middlesex. This latter was used for an engraving (1724) by B. Picart, retained in the National Portrait Gallery, London.