Cromwell was born in
Huntingdon on 25 April 1599
 to Robert Cromwell and Elizabeth Steward. The family's estate derived from Oliver's great-grandfather, a
Welshman named Morgan ap William. He was a brewer from
Glamorgan who settled at
Putney in London, and married Katherine Cromwell (born 1482), the sister of
Thomas Cromwell, chancellor to Henry VIII. The Cromwell family acquired considerable wealth by taking over monastery property during the Reformation. Morgan ap William was a son of William ap Yevan of Wales. The family line continued through
Richard Williams, alias Cromwell, (c. 1500–1544),
Henry Williams, alias Cromwell, (c. 1524 – 6 January 1604),
[b] Henry VIII strongly suggested that the Welsh should adopt surnames in the English style rather than taking their fathers' names as Morgan ap William and his male ancestors had done. Henry suggested to Sir Richard Williams, who was the first to use a surname in his family, that he use Cromwell, in honour of his uncle
Thomas Cromwell. For several generations, the Williams super-added the surname of Cromwell to their own, styling themselves Williams alias Cromwell in legal documents (
Noble 1784, pp. 11–13), then to Oliver's father Robert Cromwell (c. 1560–1617), who married Elizabeth Steward (c. 1564 – 1654), probably in 1591. They had ten children, but Oliver, the fifth child, was the only boy to survive infancy.
 Cromwell was also a distant relation of the Tudor Royal family and through them the Welsh princely family through his descent from
Jasper Tudor through his younger daughter, Joan Tudor, as shown in the
Genealogy of the Tudors. Jasper was the uncle of
Henry VII and great uncle of
Cromwell's paternal grandfather Sir Henry Williams was one of the two wealthiest landowners in
Huntingdonshire. Cromwell's father Robert was of modest means but still a part of the gentry class. As a younger son with many siblings, Robert inherited only a house at Huntingdon and a small amount of land. This land would have generated an income of up to £300 a year, near the bottom of the range of gentry incomes.
 Cromwell himself in 1654 said, "I was by birth a gentleman, living neither in considerable height, nor yet in obscurity".
Cromwell was baptised on 29 April 1599 at
St John's Church,
 and attended
Huntingdon Grammar School. He went on to study at
Sidney Sussex College, Cambridge, then a recently founded college with a strong Puritan ethos. He left in June 1617 without taking a degree, immediately after the death of his father.
 Early biographers claim that he then attended
Lincoln's Inn, but the Inn's archives retain no record of him. Fraser concludes that it was likely that he did train at one of the London
Inns of Court during this time.
 His grandfather, his father, and two of his uncles had attended Lincoln's Inn, and Cromwell sent his son Richard there in 1647.
Cromwell probably returned home to Huntingdon after his father's death. As his mother was widowed, and his seven sisters unmarried, he would have been needed at home to help his family.
Marriage and family
Portrait of Cromwell's wife Elizabeth Bourchier, painted by Robert Walker
On 22 August 1620 at
Fore Street, London,
 Cromwell married
Elizabeth Bourchier (1598–1665). Elizabeth's father, Sir James Bourchier, was a London leather merchant who owned extensive lands in
Essex and had strong connections with Puritan gentry families there. The marriage brought Cromwell into contact with
Oliver St John and with leading members of the London merchant community, and behind them the influence of the Earls of
Holland. A place in this influential network would prove crucial to Cromwell’s military and political career. The couple had nine children:
- Robert (1621–1639), died while away at school.
- Oliver (1622–1644), died of
typhoid fever while serving as a Parliamentarian officer.
Bridget (1624–1662), married (1)
Henry Ireton, (2)
Richard (1626–1712), his father's successor as Lord Protector
Henry (1628–1674), later
Lord Deputy of Ireland, married Elizabeth Russell (daughter of
Sir Francis Russell).
Elizabeth (1629–1658), married
- James (b. & d. 1632), died in infancy.
Mary (1637–1713), married
Thomas Belasyse, 1st Earl Fauconberg
- Frances (1638–1720), married (1) Robert Rich (1634–1658), son of
Robert Rich, 3rd Earl of Warwick, (2)
Sir John Russell, 3rd Baronet
Crisis and recovery
Little evidence exists of Cromwell's religion at this stage. His letter in 1626 to Henry Downhall, an
Arminian minister, suggests that Cromwell had yet to be influenced by radical Puritanism.
 However, there is evidence that Cromwell went through a period of personal crisis during the late 1620s and early 1630s. In 1628 he was elected to Parliament from the
county town of
Huntingdon. Later that year, he sought treatment for a variety of physical and emotional ailments, including valde melancholicus (depression), from the Swiss-born London doctor
Theodore de Mayerne. In 1629 he was caught up in a dispute among the gentry of Huntingdon over a new charter for the town, as a result of which he was called before the
Privy Council in 1630.
Oliver Cromwell's house in
In 1631 Cromwell sold most of his properties in Huntingdon—probably as a result of the dispute—and moved to a farmstead in nearby
St Ives (then in Huntingdonshire, now in Cambridgeshire). This signified a major step down in society compared with his previous position, and seems to have had a significant emotional and spiritual impact. A 1638 letter survives from Cromwell to his cousin, the wife of Oliver St John, and gives an account of his spiritual awakening. The letter outlines how, having been "the chief of sinners", Cromwell had been called to be among "the congregation of the firstborn".
 The language of this letter, which is saturated with biblical quotations and which represents Cromwell as having been saved from sin by God's mercy, places his faith firmly within the
Independent beliefs that the
Reformation had not gone far enough, that much of England was still living in sin, and that Catholic beliefs and practices needed to be fully removed from the church.
Along with his brother Henry, Cromwell had kept a smallholding of chickens and sheep, selling eggs and wool to support himself, his lifestyle resembling that of a
yeoman farmer. In 1636 Cromwell inherited control of various properties in
Ely from his uncle on his mother's side, and his uncle's job as
tithe collector for Ely Cathedral. As a result, his income is likely to have risen to around £300–400 per year;
 by the end of the 1630s Cromwell had returned to the ranks of acknowledged gentry. He had become a committed Puritan and had established important family links to leading families in London and