"Oliver Cromwell" is sung to the first ("A") section of the Polonaise, including the well-known main theme; it does not use the "B" section. The piano introduction is accompanied by a spoken-word introduction, setting a tone of macabre humour ("The most interesting thing about King Charles the First is that he was five foot six inches tall at the start of his reign, but only four foot eight inches tall at the end of it"), as are the subsequent connecting passages. All three instances of the main theme are given a tutti chorus followed by a recounting of the battles and other events of the period; sound effects are added, mostly sounds of battle and of horses. To the interlude is set King Charles I's trial and execution, with rubato adding atmosphere; the only sound effect is implied to be that of Charles's head falling (followed by a solitary giggle from Cromwell).
John Pym's Solemn League and Covenant; this (1643) agreement between Scottish Covenanters and English Parliamentarians respecting the Presbyterian church in Scotland and (ostensibly) committing England to Presbyterianism was influential in persuading the Scots to deliver Charles I to Parliament (in 1647)
Second theme: 1647 – 19 August 1648
"handed ... over to Oliver Cromwell and his warts" refers to Cromwell's famous instruction to Peter Lely to paint him "warts and all"
Second Civil War; the Independent leanings of the Army led to conflict with the Presbyterians in Parliament, a disagreement exploited by the Royalist faction
Battle of Preston (1648), Lancashire; the final battle of the Second Civil war was an overwhelming victory for the Independents ("Roundheads") over the combined Royalist ("Cavaliers") and Presbyterian armies
