The image still has dramatic force today. On 9 November 1953, as the rain fell in torrents in Phnom Penh, King Norodom Sihanouk stood with the departing French High Commissioner, Jean Risterucci, and the Commander of French forces in Cambodia, General de Langlade, to watch a farewell march-past by French troops as national sovereignty returned to Cambodian hands.

King Norodom Sihanouk lights a flame for unknown soldiers at the Independence Monument in 1968. The King treasured this moment, just as he treasured the description he learnt that de Langlade had given of him not long before. When some of de Langlade's officers had suggested that Sihanouk was a "madman", the general had replied, "Gentleman, the King is mad, but he is a madman of genius!"

Adding spice to this description, so far as the King was concerned, was the fact that he had known de Langlade in different circumstances. For the general had commanded the French army's cavalry school in Saumar when Sihanouk had been a student there.

November 1953 was a time of hope and celebration. Above all the transfer of sovereignty to Cambodia was the culmination of King Sihanouk's 'Royal Crusade', the campaign the monarch had begun ten months earlier when he suddenly left the Cambodian capital for France, supposedly for a holiday.

Viewed with the perspective provided by the passage of 50 years, it is difficult not to conclude that the "Royal Crusade" leading to Cambodia's independence was King Sihanouk's single greatest political achievement. Only his decision to abdicate two years later in order to take an ever-deeper role in Cambodia's political life seems in the same class.

It remains a story worth telling in some detail. And given the personalities involved, it is not surprising that it is a story that contains elements of both triumph and tragi-comedy.

At the beginning of 1953, the French military high command in the countries of Indo-China still believed it was possible to win the war against the communist-led Viet Minh.

Since this was so, they took little account of Cambodia's internal politics.

If Sihanouk wished to rule without a parliament, as he had chosen to do from January 1953, the French government and its civil and military representatives in Cambodia did not see this as a matter for much concern. Indeed, there is every reason to believe that many French politicians and officials saw this development as favouring their own interests.

In doing so they made two cardinal errors. They failed to appreciate the extent to which Sihanouk had matured from the malleable figure they had placed on the throne in 1941, and they had not reckoned on the extent to which he had gathered about him a group of politicians on whom he could rely to run the domestic affairs of Cambodia while he pursued the cause of independence abroad.

French misjudgments were soon apparent as Sihanouk began his campaign after taking up residence in the South of France. From there, in March, he sent a letter to the French President, Vincent Auriol, calling for Cambodian independence. It did not even bring a reply.

A second letter, sent two weeks later, brought the blandest of responses. The French government was studying his two letters, Auriol assured him; meanwhile he invited the King to lunch.

Worse was to come. No progress was made at Auriol's lunch, and shortly after Sihanouk was told by a senior French official that his actions in calling for independence were "inopportune".

This rebuff hardened the King's resolve to take his case to a wider international audience by travelling to Canada and the United States. As he made his travel plans, the French blundered again, telling his uncle, Prince Monireth, that Sihanouk should show "prudence" in his dealings with the Canadians and Americans.

Sihanouk was well aware that the argument most likely to sway North American opinion was that failure to grant Cambodia independence would play into the hands of the communist forces in Indo-China. What he had failed to anticipate, to use his own words, was the "cart before the horse" arguments advanced by the US Secretary of State, John Foster Dulles.

Communism was certainly the common enemy, Dulles, agreed, but the way to defeat it was by backing the French. Unless Sihanouk did so, then Cambodia would be lost to the "Reds".

Offended by Dulles's views, there was worse to come in Sihanouk's eyes. Not only did President Eisenhower fail to receive him, a maladroit State Department official suggested he might use his free time in Washington to attend a circus.

This unhappy Washington interlude set the tone for Sihanouk's later dealings with the United States, as he concluded that American politicians and officials simply did not take him seriously. Then, following a brief return to Cambodia, he sought to dramatize his demands for independence by going into temporary "exile" in Thailand in June, a move made without prior notice to the Bangkok government.

This exile proved to be a dead end, too, as the Thai government of the day, headed by Marshal Pibul, was less than helpful, telling the King that he had to regard himself as no more than a "plain political refugee". Humiliating though the experience was, his lack of welcome in Thailand was the low point that heralded the start of Sihanouk's remarkable series of successes and the final achievement of his goal.

Back in Cambodia after an absence of only seven days, Sihanouk announced he was forming a popular militia to oppose the various armed dissident groups that were ranging the countryside. Tens of thousands rallied to the King's call, including some Cambodian soldiers who had been under French command.

The call to the colours could not have been made at a better time, since the Laniel government in Paris had hesitantly come to the conclusion that the war in Indo-China had to be brought to an end. With Vietnam as the main battlefield, the French realised that granting King Sihanouk's demands for independence was a price worth paying as they contended with the much greater challenge posed by the Viet Minh.

Final negotiations began with the French in August and with the Cambodian side led by Sihanouk's staunch supporter, the ever-faithful Penn Nouth. Throughout this period Sihanouk remained in Siem Reap to underline his own refusal to deal directly with the French until independence was achieved.

By the end of October 1953, agreement was reached on all matters and King Sihanouk returned to Phnom Penh by road, cheered by crowds along the length of the route.

With the King back in the capital, a now-famous exchange between Sihanouk and General de Langlade took place.

"Sire, you have whipped me," the general said to Sihanouk in the course of his final courtesy call.

"But no, General," Sihanouk replied, "I have followed as best I can the excellent tactics you taught me at Saumur. I have just behaved as a pupil worthy of General de Langlade."

Historians will remain divided over the events that followed the achievement of Cambodian independence on November 9, 1953. Like so many other post-colonial settlements, the triumph of the moment was not destined to be followed by an untroubled future.

The judgments to be made of the years that followed will vary from individual to individual. But however critical those judgments might be, there can surely be no denying King Sihanouk his place of honour in the achievement of independence in 1953.

Milton Osborne, the author of Sihanouk: Prince of Light, Prince of Darkness (1994), has been an observer of Cambodian politics since 1959.