Monaco's history: a sovereignty that waited on an heir

How the Rock became a fortress before Monaco existed

Hecataeus of Miletus is the first writer known to name the place, as "Monoikos, a Ligurian town". Strabo called the harbour Monoikon limen and read Monoikos, "the solitary one", as another name for Heracles, who had a temple there. Wikipedia's account allows that the name may be an alteration of an older Ligurian one, and records that no temple to Hercules has been found. Phocaeans from Massalia founded a colony in the 6th century BC, and after the Gallic Wars the port passed into the Roman province of the Maritime Alps. Virgil wrote of "that castled cliff, Monoecus by the sea".

The centuries after the Western Empire fell in 476 are a list of owners: Odoacer, the Ostrogoths, Justinian's Romans in the mid-6th century, the Lombards in the 7th, then the Franks. Saracen raids in the 8th century left the place damaged, and the monks of Saint-Pons in Nice, who held it from 1075, rebuilt it. A church of St Mary and a borough around it appear in the 11th century.

The state begins with a grant to somebody else. In 1191 the emperor Henry VI gave the area to Genoa, in return for suppressing pirates according to Wikipedia's main Monaco article. On 10 June 1215 a detachment of Genoese Ghibellines under Fulco del Cassello began a fortress on the summit of the Rock, and settlers were offered land grants and tax exemption to live around its base. The date is often given as the start of Monaco's modern history. From that date a city meant to hold the Rock, and what followed was a long quarrel over who would.

How the Grimaldis took the Rock and kept it

The Grimaldis were a Genoese family, descended from a 12th-century consul named Grimaldo, and they led the Guelph faction that backed the papacy against the Ghibelline supporters of the empire. Banished from Genoa in 1271, they fell back on castles in Liguria and Provence. In 1297 Francesco Grimaldi, known as Malizia, took the fortress on the Rock, by tradition with his men dressed as Franciscan friars. The Wikipedia article on the House of Grimaldi calls the story "largely anecdotal", on the ground that Guelphs and Ghibellines both took and abandoned the castle in those years because it was well placed for raids on Genoa.

Francesco was evicted within a few years and the contest ran on for another century. The family acquired Menton in 1346 and Roquebrune in 1355, which made the territory almost ten times larger. In 1395 Giovanni and Luigi Grimaldi used civil strife in Genoa to seize Monaco again, and Britannica records that they lost it shortly afterwards to the French. In 1419 a branch of the family bought Monaco from the Crown of Aragon, and that purchase is the possession that lasted.

The title came later and the sources date it differently. Wikipedia's Monaco article has Honoré II styling himself Prince from 1612; Britannica dates the family's assumption of the title to 1659.

Which protectors Monaco moved between

A lordship of one rock and two small towns survived four centuries by attaching itself to a larger power, and by renegotiating whenever that power changed. Britannica summarises the pattern as an alliance with France broken from 1524 to 1641, when the Grimaldis were under Spanish protection.

How Spain and France each recognised the prince

The Treaty of Burgos of 1524, which some accounts call the treaty of Tordesillas, placed Monaco under Spain as an autonomous state for about a century, with a Spanish garrison in the fortress. The emperor Charles V also granted the family the Marquisate of Campagna in southern Italy, held from 1532 to 1641. Honoré II secured recognition of his sovereignty from Spain in 1633 and then changed sides. The Treaty of Péronne of 1641 brought French protection, and in 1642 he was received at the court of Louis XIII as a duc et pair étranger. From 1642 to 1715 the family used the title Duke of Valentinois. The princes spent most of their lives in Paris as vassals of the French kings while remaining sovereign in Monaco, and they married into the French and Italian nobility.

Why the Grimaldi name outlived the Grimaldi line

The male line ran out in the early 18th century. In 1715 Jacques Goyon de Matignon, a French noble, married Louise-Hippolyte, the last agnatic Grimaldi heir. She abdicated in his favour, and a condition of his becoming prince was that he take the name and arms of Grimaldi. His male-line descendants ruled under that name from 1731 to 1949. Carrying the dynasty through a woman whose husband adopts the name was used again in the 20th century, and the house law still requires the reigning prince or princess to bear the surname Grimaldi.

What the Revolution took

In 1789 the French seized the princely financial assets. In 1793 Monaco was annexed as part of the département of Alpes-Maritimes: the family was imprisoned and later freed, the art collections were sold off, and the palace became a hospital and poorhouse. French rule lasted until 17 May 1814, when Honoré IV was restored. The Congress of Vienna put the principality under the Kingdom of Sardinia in 1815, confirmed by the Treaty of Stupinigi in 1817. Honoré IV created the Compagnie des Carabiniers du Prince in 1817 to guard the principality and the family. Italian was the official language through the Sardinian years, and French replaced it in 1860.

Why Monaco gave up almost all its land

Two towns carried the revenue. By the 1840s the Grimaldis had ruled Menton and Roquebrune for more than 500 years, and the townspeople had grown weary of heavy princely taxation, while Sardinian intervention had accustomed them to lighter taxes. In 1848 both towns seceded as the Free Cities of Menton and Roquebrune, hoping for annexation by Sardinia, and in 1849 they became a separate Sardinian protectorate. France protested.

The ground under the whole arrangement moved in 1860. By the Treaty of Turin, Sardinia ceded the County of Nice and Savoy to France and withdrew its forces from Monaco, which was left surrounded by France and under French protection once more. Charles III then gave up his claim to the two towns, some 95% of the principality's territory at the time. The price is recorded two ways by the same encyclopedia: four million francs in Wikipedia's History of Monaco, 4,100,000 francs in its main Monaco article. The Franco-Monegasque Treaty of 2 February 1861 recognised both the transfer and Monaco's sovereignty.

The sale came with a promise that later treaties quote. The treaty of 1918 cites "the additional articles of the treaty of 2 February 1861", under which the prince undertook for himself and his successors never to alienate the principality, in whole or in part, to any power other than France. A customs union followed in 1865, and since 1861 Monaco's military defence has been the responsibility of France.

Before 1861 a protector could be exchanged for another, as Spain had been exchanged for France in 1641. After 1861 France surrounded the principality on the landward side and held a reversion over it, and the state that remained had lost the towns that had paid for it.

How a casino paid for the state that remained

The casino plan is older than the loss of the towns. It was drafted under Florestan I in 1846, when the regime of Louis-Philippe would not let a dignitary such as the Prince of Monaco run a gambling house and the House of Grimaldi was heavily in debt. The first casino opened only after Charles III came to the throne in 1856. Its concessionaire failed to draw enough custom, moved premises several times and sold the concession to François and Louis Blanc for 1.7 million francs. The Blancs had made their money at Homburg, a German spa town.

The opening date differs between the sources. The Société des Bains de Mer, founded in 1863 by decree of Charles III, dates the opening of its casino to spring 1863, five years after the first stone was laid on the Plateau des Spélugues, until then arid ground planted with olive and citrus trees. Britannica says the casino was built in 1861, and Wikipedia's Monaco article has the Blancs opening Le Grand Casino in 1858. On 1 June 1866 Charles III decreed that the company's facilities would be called Monte Carlo.

The company's own history counts more than 170,000 visitors in 1869, and Wikipedia credits the new French railway with much of the traffic. In the same year the principality stopped collecting income tax from its residents, which Wikipedia attributes to the casino's revenue, and Monegasque citizens were barred from the gaming rooms unless they worked there. Charles Garnier, architect of the Paris Opera, rebuilt the casino from 1878 with a theatre where Sarah Bernhardt played on the opening night of 25 January 1879.

In the years after the casino opened, Monaco also founded its Oceanographic Museum and the Monte Carlo Opera House. The museum, built in 1910, was the work of Albert I, an oceanographer who also founded the Oceanographic Institute in Paris. The Monte-Carlo Rally began in 1911 and Diaghilev's Ballets Russes arrived at the opera house the same year. The state took over the casino's operations in 1967, according to Britannica.

Why Monaco's independence came to depend on an heir

Why the succession became a French question

Albert I was an absolute ruler until the Monegasque Revolution of 1910. The constitution he granted on 5 January 1911 shared legislative authority with a National Council elected by Monegasque men and set out individual freedom, religious freedom and the right of ownership. He suspended it during the First World War.

The same years exposed the line. Under the succession rules in force before 1911 the throne would have passed to Prince Wilhelm of Urach, a German, and Wikipedia's account records that Raymond Poincaré threatened French annexation if a German inherited. Charlotte Louvet was legitimised in 1911 and made successor, and the House of Grimaldi article counts her among the adoptive heirs that the arrangements of the period allowed. Her husband, Count Pierre de Polignac, took the Grimaldi name and arms as a condition of the marriage, repeating the device of 1715. The losing side's claim resurfaced a century later: in 2018 Count Louis de Causans, of a cadet branch, sued France for €351m, arguing that his great-grandfather Aynard de Chabrillan should have inherited.

What the treaty required of every prince

The treaty signed in Paris on 17 July 1918 settled the crisis on French terms. Article 1 committed France to defend Monaco's independence and guarantee its territory as if it were part of France, and bound the prince to exercise his sovereignty in perfect conformity with French political, military, naval and economic interests. Article 2 required prior agreement with France on international relations and on any regency or succession, which could pass only to a person of French or Monegasque nationality approved by the French government.

Article 3 repeated the promise of 1861 never to alienate the principality to any power other than France, and it provided for a vacant crown, "notably for want of a direct or adoptive heir". In that case the territory would form an autonomous state under the name State of Monaco, under French protection, and private property not in public use would be bought out by that state with French help if needed. The Treaty of Versailles endorsed the arrangement in 1919.

Read together, the articles made a sovereign Monaco last exactly as long as there was a direct or adopted heir acceptable in Paris.

How occupation and a tax quarrel tested the protection

Louis II was pro-French and tried to keep Monaco neutral in the Second World War, while supporting the Vichy government of his old army colleague Marshal Philippe Pétain. Wikipedia's account describes a population mostly of Italian descent, many of them supporters of Mussolini. Italian troops occupied Monaco on 11 November 1942 by the dating in Wikipedia's History of Monaco; its main Monaco article gives 1943. German forces followed in September 1943 and began deporting the Jewish population. René Blum, founder of the Ballet de l'Opéra in Monte Carlo, was arrested in his Paris home and murdered at Auschwitz. In August 1944 the Germans executed the resistance leaders René Borghini, Joseph-Henri Lajoux and Esther Poggio, and Allied forces liberated the principality on 3 September 1944. On 27 August 2015 Albert II apologised for Monaco's part in handing over 90 Jews and resistance fighters, of whom nine survived.

Rainier III succeeded his grandfather Louis II in 1949 and married the American actress Grace Kelly in April 1956. The next quarrel with France was over tax. In 1959 Rainier suspended part of the constitution and dissolved the National Council after a disagreement over the budget, and in 1961 he appointed a national assembly in its place. Monaco's refusal to tax its residents and the foreign businesses based there produced a crisis with France in 1962, and Wikipedia records that Charles de Gaulle blockaded the principality in 1963. The compromise taxed French citizens with less than five years of residence at French rates, and taxed Monegasque companies doing more than 25% of their business outside the principality.

The constitution of 17 December 1962 came out of the same crisis. It restored the National Council, gave women the vote in all elections, abolished the death penalty and set up the Supreme Tribunal, and the government's own Council of Europe history notes that it could no longer be suspended. Its succession article operated inside the limits of the 1918 treaty for the next forty years.

What changed when the dynastic clause was rewritten

Monaco joined the United Nations in 1993 with full voting rights. The larger change came in 2002, in two instruments. Law no. 1249 of 2 April 2002 revised the constitution, and on 24 October 2002 France and Monaco signed a treaty replacing that of 1918. The CEFAN archive, which publishes the text, describes the shift as a move from the "amitié protectrice" of 1918 to a "communauté de destin".

Under the 2002 treaty the succession follows the Monegasque constitution and France is told of any change in the order. Article 10 of the constitution runs first through the direct legitimate descendants of the reigning prince, then through the prince's brothers and sisters and their descendants, and, failing all of them, to a collateral designated by the Crown Council on the advice of the Regency Council. The heir must hold Monegasque nationality on the day the succession opens. Britannica notes that the revision added females and their legitimate children to the line; the House of Grimaldi article notes that adoptive heirs, which the 1918 treaty had allowed, were excluded.

The 2002 revision also prepared membership of the Council of Europe, which followed in 2004. It widened the National Council's powers over legislation and treaties, extended civil rights to women and foreign nationals, and lowered the age of majority to 18. The first succession under the new rules came in 2005: Rainier III handed his duties to his only son on 31 March 2005 and died six days later, and Albert II formally assumed the throne on 12 July 2005.

How Monaco has added land since the sale

The 95% given up in 1861 has never been recovered by treaty. Land added since has come from the Mediterranean. The BBC reported in 2025 that a quarter of Monaco's territory has been reclaimed since 1907, including the beach at Larvotto, Port Hercules and the Fontvieille district west of the palace. Mareterra, a six-hectare district off Larvotto unveiled in December 2024 after the plan was announced in 2013, added about 3% to the territory, on 18 concrete caissons set on the seabed.

The population living on that ground stood at 38,857 on 1 January 2025. Monegasque nationals are a minority of it: the BBC counted nearly 10,000 of them in 2025, and none of the new Mareterra residences had been reserved for them.