interregnum

With the act of union adopted by the recalled Rump Parliament on this day in 1659 following the resignation Richard Cromwell after the chaotic death of his father Oliver Cromwell, England and Wales were declared a republican Commonwealth, a maneuverer that set in motion the restoration of the monarchy from exile in 1660 with the proclamation one year to the day later that heir Charles II had been the lawful regent since the death of his predecessor, constitutionally the undoing of all that had transpired in the preceding nineteen years.
In May of 1649, the original Rump Parliament (also called the Long Parliament) took power after the trial and execution of Charles I and this sitting legislature was dissolved in 1653 with executive powers vested in the Army Council, which then elevated Oliver Cromwell as Lord Protector of a united British isle—Scots and Irish resistance finally suppressed at the time during what was referred to as the third civil war that ushered in this second, brief republic—Cromwell’s government itself became untenable after a term of five years, punctuated by rampant purges, Irish genocide, cronyism (with political succession an afterthought and apparently a dynastic one was acceptable), harmonisation with religious authorities and the shuttering of the theatres.