THIS IS THE SECOND BOOK by Bradley Smith on the subject of the Nuremberg trial of the surviving World War II Nazi leaders by the victorious four powers. His first was Reaching Judgement at Nuremberg, in 1977, which was remarkable in its scholarship. The author, more than 30 years after the trial, found the files and notes of several of the judges, most notable among them being the papers of Francis Biddle, former attorney general of the United States, who as the American judge kept copious notes on the witnesses, the arguments, the lawyers, and even on his colleagues, the other judges.

This second volume -- The Road to Nuremberg -- describes the preparation for this international trial by the United States, Britain, Russia and France, as the German armies started to crumble in 1945. The "road" was -- almost wholly -- an American road, Smith argues.

The fact there was any trial at all was due to the persistence of the American government, particularly the War Department, whose lawyers, whether in uniform or in civilian clothes, insisted from the beginning that the Nazis were entitled to a fair trial. Curiously, the British, including Winston Churchill, were in favor of compiling a list of the top Nazis and shooting them as soon as they could be captured. For awhile, this view was also held by Henry Morgenthau, the American secretary of the treasury.

In fact the "road to Nuremberg" originated with Henry Morgenthau's hard fight for a "scorched earth" policy which would deindustrialize Germany. But the "Morgenthau Plan" ran up against the redoutable Henry Stimson, perhaps the leading public servant of this century. He had been secretary of war under Taft, secretary of state under Hoover, and was once again in World War II the secretary of war under Roosevelt. He was also a leading international lawyer. He believed in the rule of law and would have no truck with the concept of "shooting out of hand."

President Roosevelt vacilliated over the subject of the Morgenthau Plan for the economic destruction of Germany while his cabinet fought bitterly about it. In fact he and Churchill did agree to it in writing at the Quebec summit meeting. But Stimson was a wily warrior and finally convinced Roosevelt, who was at the time tired and ill and near his death, to abandon it.

Harry Truman became president in 1945. Stimson, with the able help of his assistant secretary, John McCloy -- later to become the American administrator of occupied Germany -- carried on the fight for a four-power trial. They quickly convinced Truman. By this stage the Justice Department and, in lukewarm fashion, the State Department had joined in their point of view. The War Department meanwhile pressed hard for a charge against the Germans of "aggressive war," which had not existed as a crime up to Nuremberg. Their opponents replied that this charge created as ex post facto crime.

Judge Sam Rosenman, who had been Roosevelt's White House counsel and was still active for Truman, took the War Department position to San Francisco where the first international meeting had convened to create the United Nations. The Russians supported the concept of a trial and the British, still in favor of summary shooting, finally gave in. The final touches were put on the charter for the trial at a London meeting in July 1945. The trial itself began at Nuremberg in September 1945.

As an author, Bradley Smith has two virtues. He writes well, clearly and succinctly. He has also thoroughly examined every file on his subject in the United States and Great Britain. He has patiently and laboriously reconstructed the timetable of the scores of meetings in Washington where the battles over the trial's form took place within the American government. It is difficult to see how anyone can surpass him in the future even though there are several more books on Nuremberg now in process.

There are errors to be sure. Smith confuses William Bundy, the son, with his father Harvey Bundy, who was the adviser to Stimson. President Truman was never a judge, and his subordinate would be startled to find him described as "a man with a near-mystic faith in the Bench." Will Clayton was an undersecretary of state and was never an official in the treasury.

But these are minor errors. They do not detract from the author's brilliant performance in telling us, with infinite detail, how the Nuremberg trial came to be. Whatever else it was, the judgment at Nuremberg made clear to the world, then and now, the sins, the brutality, the killings, the mass extermination of the Nazi government.