Short answers, pulled from the story.
The English Civil War grew from a prolonged conflict between Charles I and Parliament over taxation, religious policy, and the limits of royal power. Charles's "Personal Rule" from 1629 to 1640, during which he levied taxes including ship money without Parliamentary consent and imposed High Anglican worship through Archbishop William Laud, alienated Parliament and triggered a Scottish rebellion that forced him to reconvene Parliament on its own terms.
The English Civil War began in 1642 and concluded with the Parliamentary victory at Worcester on the 3rd of September 1651. Historians divide it into the First English Civil War (1642-1646), the Second English Civil War (1648-1649), and the Anglo-Scottish war of 1650-1652, sometimes called the Third English Civil War.
Charles I was executed on the 30th of January 1649 after a High Court of Justice found him guilty of treason as a "tyrant, traitor, murderer and public enemy." His secret treaty with the Scots in December 1647, known as the "Engagement", which triggered the Second Civil War, was central to Parliament's decision to try rather than negotiate with him. He was beheaded on a scaffold outside the Banqueting House of the Palace of Whitehall.
Historical records count 84,830 combat dead from the English Civil Wars, with a conservative total estimate of 190,000 dead in England when war-related disease is included, from a population of about five million. Ireland suffered the worst losses: William Petty estimated around 616,000 dead from plague, war, and famine, representing approximately 41 per cent of Ireland's pre-war population of about one and a half million.
Oliver Cromwell rose from a member of the 1628 Parliament to become the dominant military and political figure of the conflict. He formed the disciplined "Ironsides" cavalry in 1643, helped design the New Model Army under Thomas Fairfax in 1645, and commanded decisive victories at Marston Moor, Naseby, Preston, Dunbar, and Worcester. After Charles I's execution in 1649, he ruled as Lord Protector until his death in 1658.
The English Civil War resulted in the execution of Charles I in 1649 and the establishment of the Commonwealth of England, followed by Oliver Cromwell's Protectorate. The Stuart monarchy was restored under Charles II in 1660, but with Parliament's consent and subject to constitutional constraints that set England and Scotland on course toward a parliamentary monarchy. Both Ireland and Scotland were temporarily incorporated into the Commonwealth during the conflict.