Born at Knole House, Kent, son of Sir Thomas Waller, the Lieutenant of Dover Castle. During his childhood and youth, Waller experienced several narrow escapes from accidents and illness which he regarded as signs of his preservation as a special instrument of God's purpose. He attended Magdalen College, Oxford, then travelled in France and Italy, gaining his first military experience in 1617 when he joined a company of English volunteers fighting for the Venetian army. In 1620, Waller joined Sir Horace Vere's expedition to the Palatinate to rescue Elizabeth of Bohemia, where he first befriended Ralph Hopton. Hopton and Waller served as members of Elizabeth's lifeguard at Prague. After the defeat of the Bohemians at the battle of the White Mountain (November 1620), they escorted Elizabeth and her children through the snow in her escape to Frankfurt.
When Waller came of age, he inherited a substantial fortune. He was knighted by James I in June 1622. Two months later, he married Jane Reynell, only daughter and heiress of a prosperous Devonshire family. Jane died in May 1633, after giving birth to a son (1631) and daughter (1633). Waller built an impressive monument to her in Bath Abbey in which he is represented in armour beside her. A few years later, he married Anne Finch, daughter of the Earl of WInchelsea and a zealous Puritan, with whom he had four children. Waller involved himself in land and property dealing until 1640, when he stood for Parliament. He was initially unsuccessful, but was finally elected to the Long Parliament in May 1642 as MP for Andover in Hampshire.
Waller did not hesitate to support Parliament on the outbreak of the First Civil War in August 1642 — though Royalists attributed his choice to Lady Waller's influence over him. He contributed generously to Parliament's war fund and raised his own regiment of horse. In one of the earliest actions of the war, Waller captured Portsmouth for Parliament in September 1642. The following month he fought at Edgehill, where his regiment was scattered in Prince Rupert's charge. Like Cromwell, Waller quickly realised the importance of training cavalry to match the Cavaliers.
During the last months of 1642, Waller secured the south-western approaches to London. He captured Farnham Castle, Winchester, Chichester and Arundel Castle in quick succession, becoming the hero of London and earning the nickname "William the Conqueror". His string of victories continued into the spring of 1643, when he was appointed Major-General of the West. He secured the vital port of Bristol for Parliament, captured Malmesbury and scattered Lord Herbert's newly-recruited Welsh levies at Highnam. Waller advanced further west, capturing Ross-on-Wye, Monmouth and Chepstow, and threatening to invade the Royalist recruiting-grounds of Wales. He was finally driven back by Prince Maurice at Ripple Field in April 1643. Waller then began a campaign where he fought against his old comrade-in-arms Sir Ralph Hopton, who was appointed commander of the combined Royalist armies in the west. Waller was narrowly defeated at Lansdown (5 July 1643), then suffered what he called his "dismal defeat" at Roundway Down (13 July 1643).
“...That great God who is the searcher of my heart knows with what a sad sense I go upon this service, and with what a perfect hatred I detest this war without an enemy; but I look upon it as sent from God and that is enough to silence all passion in me ... We are both upon the stage and must act such parts as are assigned us in this tragedy. Let us do it in a way of honour and without personal animosities...”
From Waller's letter to Sir Ralph Hopton,
16th June 1643
Despite this setback, Waller remained popular in London. He was regarded as a champion of the "War Party" in the House of Commons, who wanted a decisive military victory over the King. Waller's commander the Earl of Essex was associated with those who sought a negotiated settlement. Their quarrel was public knowledge. It involved Waller's complaints over lack of men and supplies as well as their political differences. In October 1643, Waller was appointed commander of Parliament's newly-formed Southern Association army. He besieged Basing House in November but abandoned the siege as news came of Hopton's advance through Hampshire and Sussex towards London. After skirmishing and siege manoeuvres through the winter of 1643/4, Waller defeated Hopton at the battle of Cheriton (29 March 1644), which was Parliament's greatest victory of the war to date and demonstrated that the Roundhead cavalry was at last equal to that of the Royalists. Waller's military reputation was at its height. He was particularly noted for his abilities as a tactician, often gaining an advantage through night marches and other unexpected manoeuvres.
Ordered by the Earl of Essex to shadow the King's army while Essex himself proceeded on his disastrous western campaign, Waller was defeated at Cropredy Bridge on 29 June 1644. After the humiliating surrender of Essex's army at Lostwithiel on 2 September, Waller's army was too weak to prevent the King's return to Oxford. Waller joined forces with the Earl of Manchester to prevent the King from marching on London at the second battle of Newbury in October 1644 and campaigned again in the west during the spring of 1645 with Oliver Cromwell as his second-in-command. He was beset by mutinous and disorderly troops and a shortage of money, and this was to be his last campaign. Parliament had responded to Waller's suggestion that the army should be reorganised on a national rather than a regional basis and staffed by professional officers. This led to the formation of the New Model Army in February 1645. Waller was obliged to resign his commission under the terms of the Self-Denying Ordinance in order to retain his seat in the House of Commons.
Waller continued as an active member of the Committee for Both Kingdoms until the end of the First Civil War. As a member of the Committee for Irish Affairs, he tried to persuade disbanding soldiers to re-enlist for Parliament's projected invasion of Ireland. During the summer of 1647, tension between the Army and Parliament escalated, resulting in the Army's occupation of London in August. By then a member of the Committee of Safety and identified with the militant Presbyterian faction, Waller was one of the Eleven Members forced by Army leaders to withdraw from the House of Commons. He fled to Holland, where he was joined by his wife and family. They spent a year in exile, settling at The Hague, where Waller was able to attend Elizabeth of Bohemia once again.
In June 1648, Parliament voted to re-admit the Eleven Members and Waller returned to England. However, he was excluded at Pride's Purge in December 1648 and was one of five Presbyterians arrested on suspicion of conspiring to invite the Engager invasion of England. He spent the next four years in prison, first at St James Palace, then Windsor Castle and finally at Denbigh Castle in North Wales, where his wife died. After his release from prison in 1652, Waller married his third wife, Lady Anne Harcourt, who bore him another three children.
Waller became a Royalist sympathiser during the Commonwealth and Protectorate years and was regularly under suspicion of involvement in conspiracies against the state. He was arrested for complicity in Booth's Uprising in 1659, and spent ten weeks imprisoned in the Tower. In 1660, he was involved in the negotiations for the return of Charles II and was elected MP for Westminster in the Convention Parliament which laid the groundwork for the Restoration. After the King's return, Waller retired into private life at his estate at Osterley, Middlesex, where he died in 1668.
References:
John Adair, Roundhead General, 1969
Barbara Donagan, Sir William Waller, Oxford DNB, 2004
C.H. Firth, Sir William Waller, DNB 1899