IN the aftermath of the American civil war Henry Adams, then a young US diplomat in London, said: "I think that Lee should have been hanged. It was all the worse that he was a good man and a fine character and acted conscientiously . . . It is always the good men who, do the most harm in the world."

There were widespread calls for Lee's trial as a war criminal at the war's end, but terms of Lee's surrender at Appomatox effectively ruled out prosecution of anyone who fought for the confederacy. Hanging Lee would have been senseless and counter-productive.

Adams was one of the very few people who knew Lee and failed to fall under his spell. The distinguished British soldier, Field Marshall Viscount Wolseley, described Lee as "the greatest soldier of his age" and "the most perfect man I ever met".

Women were even more susceptible to Lee's charm. Diarist Mary Chestnut recalled meeting him for the first time in 1861. She was driving with a friend, Martha Stanard. Later she wrote: "Everything about him was so fine looking. Perfection, no fault to be found if you hunted for one. As he left us I said, `Who is it?' eagerly. `You mean you do not know! Why, it is Robert E Lee, son of Light Horse Harry Lee, the first man in Virginia.'" Another confederate matron said: "We had heard of God, but here was General Lee."

Led enjoyed female company and, throughout his life, kept up a flirtatious correspondence with several women. Yet the nearest he ever seems to have come to being unfaithful to his wife Mary - who was an invalid - was to disclose to one young confidante that he and Mary no longer slept together.

In the best biography of Lee for sixty years, Thomas tries to explain a man who was by turns a severe but loving father, a flirtatious but faithful husband, a slave-owner who disapproved of slavery and eventually freed his own slaves, a defender of traditional values who accepted change, and a soldier who worked hard for peace, even though he revelled in the freedom from middle-class conformity that only war gave him.

Soldiers make unlikely spiritual leaders for their people, especially those as taciturn as Lee. He wrote no political or spiritual tracts and his only recorded speech was three sentences long. He did not even write his famous farewell address to the army of Northern Virginia, it was done by a subordinate who kept to his brief of omitting anything that could be construed as political.

Like that other great icon of the civil war, Abraham Lincoln, Lee was a deeply moral man. Both men tried to give their beliefs a practical bent in an unaccommodating world. And like Lincoln, Lee had an almost instinctive sense of what was "right" in every sort of situation.

His finest moment, according to most historians, was when he rallied his shattered army after Gettysburg by apologising to the troops. He said, "You men have done all that men could do, the fault is entirely my own." It was a measure of the hold he had on the army that it followed him for almost another two years in the face of lengthening odds. For much of that time his troops went hungry and barefoot.

Nevertheless, Lee's truly finest moment may have been in June 1865, two months after the war ended. He was attending Sunday service at the socially exclusive Episcopalian church of St Paul's in Richmond, when a tall, well dressed and very black man rose from the congregation and strode up to the communion rail.

There was a long pause. As one witness wrote afterwards, the effect on the would be communicants was "startling ... being deeply chagrined at this attempt to inaugurate the `new regime' to offend and humiliate them ... Lee rose and took his place at the altar rail near the first communicant. Everyone else followed. Lee had moral imperatives, not ideological ones. As he explained to a fellow Confederate general later "True patriotism requires men to act exactly contrary, at one period, to that which it does at another, and the motive which impels them - the desire to do right - is precisely the same." No politician could have said that and survived, but it was accepted by Lee's contemporaries as yet another pearl of wisdom.

Like Lincoln, Lee did not believe African-Americans were the equals of white Americans but he believed slavery was an evil institution. He also believed his native Virginia was foolish to have seceded from the Union, even though he felt obliged to defend her right to be wrong.

Once the war was over he knew the only course was to rebuild the Union on the best terms possible, and that meant reconciliation and acquiescence. For the same reason he condemned attacks on freed slaves and abolitionists, and warned his former subordinates against the dangers of guerrilla war.

Along with many others, Lee was impoverished by the war. But fame has its rewards. He was offered several lucrative company directorships, the presidencies of two universities and was also invited to enter politics - first as a candidate for the governorship of Virginia and then as a possible Democratic Party candidate in the 1868 presidential election, where his opponent would have been Grant.

Instead, he accepted the presidency of Washington College in Lexington, Virginia, which was on the verge of closure. Despite his own misgivings Lee proved a gifted educator. In his brief time at Washington he quadrupled student numbers, quintupled the staff introduced scientific and technical subjects to the curriculum and was planning to establish an observatory and medical school at the time of his death.

By then, Lee had come to represent all that was best in the old republic swept away by the civil war, in much the same way as Lincoln embodied the spirit of the new republic to which it gave birth. Lincoln's elevation to secular sainthood was expedited by the assassin's bullet, but Lee's apotheosis took a little longer and might never have happened without the moral leadership he gave to the south after the war ended.

Like David Herbert Donald, in his recent biography of Lincoln, Thomas has concentrated on his subject's private life, as much as the public one. It is an especially difficult task with Lee, who confided in very few people. Perhaps the best known example of this reticence was his decision not to disclose, even to the confederate president Jefferson Davis, that he had been offered command of the union armies at the outbreak of the civil war. It only became known after he was dead.

If he had accepted the union command, the war would have been much shorter and most of the 650,000 American casualties would have been avoided. Adams was right in his judgment that it is good men who do the most harm.