It is based on the life of Oliver Cromwell, who rose to lead the Parliamentary forces during the later years of the English Civil War and, as Lord Protector, ruled Great Britain and Ireland in the 1650s.

It features an ensemble cast, led by Richard Harris as Cromwell and Alec Guinness as King Charles I, with Robert Morley as Edward Montagu, 2nd Earl of Manchester and Timothy Dalton as Prince Rupert of the Rhine.

The film received two Oscar nominations during the 43rd Academy Awards held in 1971, winning one for Best Costume Design by Vittorio Nino Novarese, but losing another for Best Original Score, composed by Frank Cordell.

At the 7th Moscow International Film Festival in 1971 it won the award for Best Actor (Richard Harris), and was nominated for the Golden Prize as Best Picture (Ken Hughes).

[3] The film received negative reviews for its many historical inaccuracies; however, much praise went to the acting (particularly Harris and Guinness), the score, and the costume design.

In fact, Charles regards himself as a devout Anglican, permitting his French Queen to practise Roman Catholicism in private but forbidding her to bring up the young Prince of Wales in that faith.

The king is eventually encircled in his headquarters at Oxford and has his fervent supporter and nephew, Prince Rupert of the Rhine, banished after he fails to hold the port of Bristol.

In fact Cromwell has retired moodily to his estate and reacts with anger to a request from his radical colleague Henry Ireton and other Parliamentarians to become king himself.

The film ends with a voice-over stating that Cromwell served very successfully for five years as Lord Protector before Charles I's son returned as king of an England "never to be the same again".

In 1960, Hughes read John Buchan's biography, Oliver Cromwell and more books before touring England and researching from historic sites to museums and archives.

[additional citation(s) needed] In its defence, George MacDonald Fraser has written, "Inevitably there are historical queries all the way through, as there are bound to be in a picture which takes its subject seriously and tries to cover so much in less than two and a half hours.

[27] The film was generally received unfavourably, with criticism of the historical inaccuracies; however the performances of its two leads, production values and score were praised.