The biggest problem Republics have faced thoughout history is establishing a stable succession and transition from power. That failure ultimately doomed Oliver Cromwell’s Commonwealth of England, Scotland and Ireland. Richard Cromwell never served in the English Civil Wars. He was passed over for the first Parliament nominated by Oliver Cromwell. He displayed no particular aptitude for public life and would probably have lived a happy life as a country gentleman.
But he was Oliver Cromwell‘s oldest surviving son. His younger brother Henry and his brother in law Charles Fleetwood were far more competent, but on Oliver Cromwell’s death on September 8, 1658 Richard was proclaimed Lord Protector. It is unclear Oliver ever actually nominated him, though he had involved Richard more closely in state affairs.
The problem for the new Lord Protector was that the Commonwealth was desperately short of funds and none of the factions respected him. With no military experience he had no control over the army. The army was suspicious that military cuts would be used to cut costs. This and other acts of the Parliament against the Army set off a collision between the two legs of the Commonwealth. Under military pressure Richard Cromwell dissolved Parliament on April 22 and recalled the Rump Parliament on May 7. By this point Richard was effectively under house arrest. The Rump agreed to pay off his debts and provide a pension and Richard Cromwell resigned on May 25, 1659.
Richard Cromwell went into exile in July 1660 after the Restoration on Charles II. He traveled across the continent under pseudonyms and did not return to England until 1680/81. He lived the rest of his live in peace dying at the age of 85 in 1712 largely forgotten.