Why Cromwell Won The English Civil War?

When the English Civil War broke out in 1642, Cromwell had military training or experience. Yet within a decade, according to one leading Royalist statesman and historian, he "mounted himself into the throne of the three kingdoms [England, Wales, and Scotland] without the name of a king but with greater power and authority than had ever been exercised or claimed by any king."
Cromwell's power arose from his military ability and his unique relationship with his troops. As soon as the war began, the creation of a pious and professional army to serve the English Parliament became his principal concern, and in 1645 he pushed for the formation of a standing army, with central funding and central direction. Under the command of Thomas Fairfax, with Cromwell as his deputy, this "New Model Army" quickly routed the main Royalist force at the Battle of Naseby (June 14, 1645), marking the beginning of a string of remarkable
victories that within a year forced Charles I to surrender. Cromwell always led his cavalry from the front, although it took its toll. But close contact with his troops paid dividends, for Cromwell managed to lead his soldiers back into battle when other units paused to pillage.
The decision to execute the king in 1649 provoked a Royalist reaction in Ireland and Scotland that threatened the security of the new republic in England and forced Cromwell back into the field.
He began his Irish offensive with a massacre of the combined forces of the Catholic Confederates and the Protestant Royalists at Drogheda (September 1649); the following month the town of Wexford, base of the Irish navy, met a similar fate. Scotland's decision to invade England in support of Charles II in 1650 forced Cromwell to leave the completion of the reconquest of Ireland to others while he focused his efforts on subduing Scotland forces. His victories first at the Battle of Dunbar (September 3, 1650) and then at Worcester (September 3, 1651) not only forced Charles II to flee to the Continent for nearly ten years, but also affected the political integration of the three kingdoms -- ruled after 1653 by Cromwell as lord protector, advised by the Council of State, and with a single Parliament meeting at Westminster -- for the first time in their
history.
Cromwell, a committed Puritan, and his godly troops attributed their successes on the battlefield to divine intervention and now set out to create a godly society by establishing a body of evangelical preachers, by reforming the legal system, and by introducing legislation such as the Blue Laws (1650) against blasphemy, cursing, drunkenness, and adultery. Cromwell believed in liberty of conscience for his fellow Christians; a truly revolutionary concept for the day -- but in every other respect he remained a social conservative. He feared the democratic ideas of the Levellers (English radicals); he believed in rule by the godly, not by the people in general. After 1649 he genuinely strove to reconcile the traditional political nation to his regime; yet in 1657 he rejected a proposal, known as the "Humble Petition and Advice," which implored him to become king.