Here’s a list of some notable countries where monarchy was re-established after abolition — with the when, the who, and the why.

1. England (and later the United Kingdom)

Monarchy abolished: 1649 (Execution of King Charles I)

Monarchy restored: 1660 (Restoration of King Charles II)

King exited: Charles I (executed).
King re-entered: Charles II.
Reason: After the English Civil War, Oliver Cromwell and the Parliamentarians ran the country as a Commonwealth and later as a military dictatorship (Cromwell as “Lord Protector”). When Cromwell died, the experiment crumbled into chaos and the monarchy was restored as the "lesser evil."

2. Spain

Monarchy abolished: 1931 (Second Spanish Republic established)

Monarchy restored: 1975 (Restoration under King Juan Carlos I)

King exited: Alfonso XIII (exiled in 1931).
King re-entered: Juan Carlos I (his grandson).
Reason: Spain went through a bloody civil war, then Francisco Franco’s dictatorship. Franco, surprisingly, arranged for the monarchy's restoration upon his death, hoping Juan Carlos would continue authoritarianism. Instead, Juan Carlos shifted Spain toward constitutional democracy. One of history’s great royal plot twists.

Monarchy abolished: 1792 (French Revolution — Louis XVI executed)

Monarchy restored: 1814 (Bourbon Restoration under Louis XVIII)

Abolished again: 1848.

King exited: Louis XVI (guillotined).
King re-entered: Louis XVIII (his brother).
Reason: Napoleon’s fall after the wars left a power vacuum. The European powers (Congress of Vienna) restored the Bourbon monarchy to stabilize the region. Napoleon briefly returned (Hundred Days) before being ousted for good.

Monarchy interrupted: 1953-1955

Monarchy restored: 1955

King exited: Sultan Mohammed V (exiled by the French).
King re-entered: Mohammed V returned and became King.
Reason: The French exiled him for supporting Moroccan independence. Popular revolt forced the French to bring him back, and the monarchy was not only restored but strengthened, leading to full independence.

Monarchy abolished: 1918 (end of Austro-Hungarian Empire)

Monarchy restored (sort of): 1920 (Regency under Admiral Horthy)

King exited: Charles IV (abdicated under pressure).
King re-entered: Charles IV attempted to return in 1921, but failed (so technically partial restoration — Hungary remained a "Kingdom without a King").
Reason: Post-World War I collapse created chaos. Hungary reverted to being a kingdom but kept the throne empty, governed by a regent. The attempt to re-seat Charles IV failed, largely due to Allied opposition.

Monarchy abolished: 1799 (Naples declared a Republic by French-backed revolutionaries)

Monarchy restored: 1799 (same year!)

King exited: Ferdinand IV of Naples.
King re-entered: Ferdinand IV.
Reason: French revolutionary forces backed the Republic, but it lasted mere months. An army of loyalists and British forces ousted the republicans, and Ferdinand waltzed back onto the throne.

Russia toyed with restoration during the Russian Civil War (1917-1922) but the Bolsheviks made sure the Romanovs stayed buried.

Cambodia’s monarchy was restored in 1993 (Norodom Sihanouk returned), after the Khmer Rouge and years of Vietnamese occupation.

Country	Exit Year	Return Year	Monarch (Exited)	Monarch (Returned)	Reason
England (UK)	1649	1660	Charles I	Charles II	Civil War, Cromwell's fall
France	1792	1814	Louis XVI	Louis XVIII	Napoleon’s defeat, Vienna deal
Spain	1931	1975	Alfonso XIII	Juan Carlos I	Franco’s death, transition
Morocco	1953	1955	Mohammed V	Mohammed V	Colonial exile ended
Hungary	1918	1920 (regency)	Charles IV	(Attempted Charles IV)	Post-WWI collapse
Naples/Two Sicilies	1799	1799	Ferdinand IV	Ferdinand IV	French expulsion
Cambodia	1970	1993	Norodom Sihanouk	Norodom Sihanouk	End of Khmer Rouge/Vietnam War