Oliver Cromwell was as effective a monarch killer as Liz Truss, but after executing King Charles I Cromwell hummed and hawed about whether or not to accept the British crowns, in the end he gave himself the modest title 'Lord Protector of the Commonwealth of England'. Cromwell incorporated Scotland into his Commonwealth, he had to occupy the country because a political union between the nations was not possible at this point, a Presbyterian country with a monarch could not be expected to voluntarily enter into a union with a Republic, this is the only time in British or Irish history that this would ever prove to be an issue.