Gaston Defferre, France's senior left-wing politician, known by the nickname "the lion of Marseilles," is dead.

For more than three decades, Defferre ran France's toughest, most turbulent city like a patriarch presiding over an unruly family. He built a political machine that rivaled anything seen in Chicago under Richard J. Daley. He was loved and hated, respected and reviled. For many Frenchmen, the white-haired 75-year-old politician was Marseilles.

In a scene that could have been borrowed from a Greek tragedy, his death occurred at the very moment when his control over the city he loved was beginning to unravel. The challenge came from the most unexpected of quarters: a Socialist politician long regarded as his most likely successor as mayor of France's second largest city.

On Monday night, Defferre lost a key vote at a Socialist Party meeting in Marseilles. He went home at 1.30 a.m. and had an unexplained fall, which cracked his skull. Alone, semiconscious and bleeding profusely, he telephoned his doctor. By the time an ambulance arrived, he was in a coma.

It was a poignant end to a political career that spanned France's postwar history. A resistance leader during the Nazi occupation, Defferre was a Cabinet minister during the postwar Fourth Republic, a left-wing presidential candidate against Gen. Charles de Gaulle and one of the founders of the modern French Socialist Party.

But it was in Marseilles -- the gateway to North Africa -- that he made his mark. His proudest boast was that he managed to govern a city that was regarded for years as ungovernable, a city known for its gangsters and drug smugglers, ruthless businessmen and corrupt politicians.

Defferre's power base in Marseilles rested on his control of local newspapers, the Socialist Party, the trade unions and the mayor's office, which he had occupied without a break since 1953. A right-wing Socialist, he won the support of middle-class voters by presenting himself as the politician best placed to keep the Communists out of city hall.

"Marseilles has never been a Socialist city. I succeeded in making it believe that it was," he once boasted.

The mayor's political strategy was captured in a celebrated Socialist election poster in 1965 that showed a picture of the old port of Marseilles emblazoned with the Communist hammer and sickle. "Jamais ca," the slogan proclaimed, "Never this." He remained an anticommunist to the end of his life, despite concluding a tactical alliance with his old political enemies in 1983.

In some ways, Defferre was an atypical representative of Marseilles, a city that alternates between violent passions and an easygoing approach to life. The descendant of a family of wealthy Protestants in an overwhelmingly Catholic country, he had the reputation of being austere, ascetic and difficult to approach. He did not touch alcohol.

A proud man, Defferre did not like to be reminded of his political mortality. When the voters of Marseilles turned against him in the first round of the 1983 municipal election in favor of a jovial conservative opponent, Jean-Claude Gaudin, he remarked: "This is not a town that one manages, it is a town that one governs, and that is something that requires character. Marseilles will return to me."

Sure enough, Defferre won reelection in a bitterly fought second round in which he collected fewer votes but more seats in the city council than Gaudin.

In the end, however, it was one of his own political children who undermined his local power base. Last September, he found himself outvoted for the first time in three decades at a local Socialist Party meeting. His victorious rival was Michel Pezet, an ambitious young lawyer whom he had personally picked as his right-hand man in 1978.

As Defferre lay dying, Socialist activists physically prevented Pezet's supporters from coming to pay their last respects. Shouts of "assassin" were heard in the hospital corridors, an indication of the emotions released Monday night when Defferre's candidate for the post of head of the regional Socialist Party federation was defeated by 109 votes to 118.

In a final tribute to his former political patron, Pezet described their differences as "derisory at the time of the final reckoning." Recognizing that he owed his own political career to Defferre, he praised the mayor's "courage and sense of duty."

President Francois Mitterrand, who was kept informed of Defferre's condition at the Tokyo economic summit, flew immediately to Marseilles today on his return to France. The two men rebuilt the Socialist Party at the end of the 1960s, turning a collection of squabbling factions into what has now become the largest political party in the country.

After the Socialist election victory in May 1981, Mitterrand put Defferre in charge of the government's decentralization program. In a country where political power has traditionally been concentrated in Paris, the decision to set up rival centers of power in the provinces was widely regarded as one of the most important changes to be carried out by the Mitterrand administration.

Political commentators today also praised Defferre for supervising the beginnings of the decolonization of French Africa while minister for France's overseas territories in the years 1956-1957. It was under his guidance that a law was passed enabling the colonies to gain local autonomy, which eventually led to full independence.

Perhaps the most fitting tribute to Defferre was paid by a long-time political associate and fellow resistance fighter, Charles Emile Loo, who remarked: "Defferre? You either hated him or you loved him -- in spite of everything."