On April 25, 1599, Oliver Cromwell was born in Huntingdon, a market town about sixty miles north of London, to Robert Cromwell and Elizabeth Steward. The family was comfortable but not grand — minor gentry who owned land, employed servants, and occupied a respectable place in the local hierarchy without approaching the wealth of the great aristocratic houses. His father held modest properties and served as a justice of the peace. Oliver grew up expecting roughly the same: a life of local administration, farming income, and parish duties. Nothing about his early years suggested he would one day govern all of England.

The Cromwell name carried more historical weight than the family's bank account. Oliver was descended from Richard Cromwell (originally Richard Williams), whose uncle Thomas Cromwell had served Henry VIII as chief minister and architect of the English Reformation before his execution in 1540. By Oliver's time, that connection was distant enough to be a family footnote rather than a source of influence. Still, he grew up in a country already shaped by the Reformation his ancestor had helped engineer — a Protestant England that was, by 1599, increasingly uncertain what kind of Protestant country it wanted to be.

Oliver attended the Huntingdon Free School under Thomas Beard, a headmaster who combined serious classical learning with an intense Protestant worldview. Beard's 1597 book The Theatre of God's Judgements argued that history was God's ongoing punishment of the wicked. That idea — that God intervenes visibly in human affairs and rewards or punishes nations and individuals according to their faithfulness — lodged itself in Cromwell's thinking and never left. In 1616, Oliver entered Sidney Sussex College, Cambridge, a college with a strongly Calvinist character. He stayed less than a year: his father died in 1617, and as the only surviving son he returned to Huntingdon to manage the family's affairs.

In 1620 he married Elizabeth Bourchier, daughter of a London merchant. The marriage was stable and, by all accounts, genuinely affectionate — their correspondence shows real warmth across decades of separation during the wars to come. They would have nine children, most of whom survived to adulthood.

Through the 1620s, Cromwell's material circumstances actually declined. He sold most of the Huntingdon properties and by the early 1630s was tenant-farming land he had once owned. Historians are not entirely certain of the details, but the picture is of a man slipping downward in the gentry scale, managing a respectable but strained household. Then, sometime in the mid-to-late 1630s, he underwent what he later described as a spiritual crisis and conversion.