The murder of American prisoners of war and Belgian civilians by the Nazi Waffen-SS began before the Battle of the Bulge was 24 hours old.

No one knows exactly when it started or how widespread it was, but in the first hours of the Germans' last great offensive of World War II late in December 1944, an SS officer herded eight American prisoners out of a house in the village of Honsfeld and shot them with a submachine gun known as a "burp gun." The same fate befell five others from another house, four from yet another, 20 or 30 out of a group of about 100 in yet another instance.

Shortly after, troopers of the same unit -- "Kampfgruppe Peiper," a special attack force named after Joachim Peiper, then 29, a regimental commander in the 1st SS Panzer Division and one of the most feared and respected officers in the Waffen-SS (armed SS) -- captured about 130 Americans, mostly from Battery B of the 285th Field Artillery Observer Battalion.

In a few minutes, 86 were dead, the others feigning death, in what became known as "the Malmedy Massacre," named for a nearby village. It was the worst atrocity that the Nazis committed against the U.S. armed forces in the European theatre.

No one seems to know exactly which units or actions the 49 Waffen-SS soldiers buried at the German military cemetery in Bitburg, West Germany, served in, but they were killed in the Battle of the Bulge. The fact that they belonged to the SS and that President Reagan agreed to lay a wreath at the cemetery, which contains the bodies of about 1,800 German soldiers killed in World War II, has cast a giant cloud over Reagan's state visit to Germany after next month's economic summit meeting in Bonn.

West German officials contend that most of the SS troopers were 18- and 19-year-old conscripts who happened to get drafted into the SS. Others contend that the Waffen-SS were primarily an elite front-line military force, separate from the concentration camp guards and secret police units.

But there is no uncertainty on one point: The Nazi SS -- short for Schutzstaffel, Guard Echelon or Elite Guard -- played the central role in the most hideous atrocities of the Third Reich, the darkest chapter in western civilization, and almost the end of it.

With their black uniforms, death's heads (a symbol of their willingness to die for Adolf Hitler) on their caps and the runic double S flashes on their collars, the SS men were the most fanatical of Hitler's followers and the terror of the entire European continent. Whatever the actual roles of the young men buried at Bitburg, the "SS" is one of the most potent symbols of evil and cruelty in history.

Members of the Waffen-SS boasted that it was the finest military fighting force ever, and they may be right even though Germany lost the war.

SS units spearheaded the Nazis' great offensive into Russia -- the 2nd SS Panzer Division, known as "Das Reich," got the nearest to Moscow in December 1941. It was the eastern army's fire brigade, thrown into the breach to close the huge gaps the Red Army tore in the German lines which became increasingly frequent as the war turned in the Soviets' favor.

An American historian, George Stein, credits the SS Panzer divisions in the Soviet Union with preventing at least two Stalingrad-sized catastrophes by saving two separate Wehrmacht armies from being encircled and destroyed. The Soviets had an almost superstitious fear of the Waffen-SS; one captured Soviet general, a corps commander, confessed that the Russians were always relieved when SS units were replaced on the line by regular German army units.

With each military triumph, the SS increasingly took on the attitude of an elite, looking at the Wehrmacht the way guardsmen always have looked on common soldiers. SS generals were among the most arrogant and independent of any, often ignoring Hitler's orders on maneuver of their units.

The Waffen-SS inflicted -- and suffered -- incredible casualties and at first horrified Wehrmacht officers with their reckless disregard of their lives. The conscription of replacements became difficult in about 1942 because of the horrifying atrocity stories and towering casualty rates. The army liked having the Waffen-SS around, however, both for its fighting prowess and to blame for the atrocities.

Members of a Waffen-SS artillery regiment committed the first Nazi military atrocity of the war in the early days of the invasion of Poland when they shot to death about 50 Polish Jews who had been conscripted to repair a bridge. During the Third Reich, complaints of such brutality, of the extermination of villages and executions of hundreds of Jews or partisans as reprisals by Germans who saw these acts as inimical to Germany's long-range interests throughout Europe, were as frequent as praise for the courage and effectiveness of the SS units.

This was particularly true in the brutal racial war against the Soviets. Joachim Peiper's SS Panzer unit was known as the "Blowtorch Battalion" because of his penchant for burning Russian villages to the foundations with flamethrowers mounted on half-tracks.

According to Charles B. MacDonald, a leading historian of the Battle of the Bulge, SS troopers going into that engagement in December 1944 were exhorted to remember their loved ones who were being killed in the Allies' bombing of German cities.

"I am not giving you orders to shoot prisoners of war but you are all well-trained SS soldiers. You know what you should do with prisoners without me telling you that," one company commander told his men.

Although most of the fighting men of the Waffen-SS did not commit atrocities, there was no clean separation. In April 1941, Heinrich Himmler, the head of the SS and the Gestapo, directed that all concentration camp guard units be part of the Waffen-SS, which would be responsible for their military training and equipment.

The Waffen-SS provided the men for the Einsatzgruppen, the mobile gas vans that killed hundreds of thousands of persons in the East, and large numbers of concentration camp guards, the Totenkopfverbande (death's head formations), were transferred to Waffen-SS units: 2,500 from the extermination squads at Auschwitz, 1,500 from Sachsenhausen. In addition, 50,000 men from the concentration camp guards became the cadres for new SS divisions formed later in the war.

Hitler formed the SS in 1925 as a personal bodyguard unit and as a counter to the SA, the Sturmabteilung, the brown-shirted storm troopers, street-brawling thugs who increasingly terrorized political rivals, Jews and anyone they suspected of being political enemies of the Nazi (National Socialist) party. The Waffen-SS was born as an internal fighting unit partly to protect the rest of the SS from the SA.

The SA's first leader was Hermann Goering but it grew under Ernst Roehm, a World War I hero, street brawler and homosexual. Hitler considered the SA an undisciplined, unreliable, potentially dangerous rabble. In 1929, he tapped Himmler, an ardent disciple and unsuccessful chicken farmer, to head the SS.

Roehm openly wanted the SA to become part of the regular army as a revolutionary people's fighting force under a ministry of defense that he himself dreamed of leading. But Hitler realized that the army was appalled by Roehm and the SA, and that he would need the army's support when he gained power, so he distanced himself from Roehm. On June 30, 1934, "The Night of the Long Knives," Hitler ordered the SS to murder Roehm, other SA leaders and assorted other political opponents. Estimates of the total number range into the hundreds.

The SS was noted from the first for its discipline and effectiveness. Himmler saw it as an elite group, by contrast with the SA, which he viewed as lower-class rabble. He emphasized recruiting the sons of nobility and the upper classes on the grounds that a base in the establishment gave the SS important support from influential Germans in the population. Initially, Himmler required that all SS recruits be able to demonstrate that they had no Jewish blood going back at least to 1750.

The SS was a potpourri of alienated intellectuals, ardent idealists, sadists, thugs, psychopaths, and cold-eyed opportunists and careerists such as Adolf Eichmann. It drew from all classes. Early on the Waffen-SS was heavy with farm boys.

No one in this collection was stranger than Reichsfuehrer SS Himmler, who as head of the SS and all the police forces was the second most powerful man in Germany and probably the only who could have toppled Hitler.

Himmler often was described as looking like a schoolmaster; his pince nez spectacles and fussy, prissy attention to details fit the description. He was a puritan about sexual conduct and broke a younger brother's engagement because his intended had something of a reputation.

But below that exterior teemed dark obsessions: hatred of Jews, whom he blamed for Germany's economic woes, a belief that it was Germany's destiny to colonize the Slavic lands to the East as the Teutonic Knights had in the 14th and 15th centuries, an obsession with returning to a Nordic "racial purity," a love of the heroes and heroines of German folklore, and fascination with medieval mythology and a range of other mystic theories.

A Roman Catholic, he organized the SS along the lines of the Jesuits (Hitler sardonically referred to him as "my Ignatius Loyola") and the early cadets' severe two years of exams, trials, vows of poverty, chastity and obedience were similar to those of the novitiate.

From the Freemasons, of whom he had a superstitious dread, Himmler learned the power of ranks and insignias and designed for his order a signet ring, dagger and coats of arms. From the legend of King Arthur, he chose 12 top subordinates, the number of the Knights of the Round Table.

Himmler had a Round Table of his own, in a 100 by 145-foot dining room in Wewelsburg Castle in Westphalia, built by a medieval robber knight and chosen by Himmler because of a Germanic legend that a hilltop castle in Westphalia would be the sole survivor of the last Slavic assault from the East.

But he also had the soul of an empire-building bureaucrat. By 1944 the Gestapo numbered about 45,000, the concentration camp guards about 40,000, the SS security force, the SD (Sicherheitsdienst, the security service) about 100,000, the security police about 65,000 and the regular police nationwide about 2.8 million. The Waffen-SS reached a peak strength of nearly a million men.

These numbers, however, seem small compared to the task that Himmler was assigned. His secret police force attempted to maintain total scrutiny over every person in Germany, and later, in conquered countries. According to some accounts there was one party official, not a member of the police forces, to report on every 40 citizens.

All this was to provide internal discipline in preparation for the Third Reich's "New Order," which was to feature the enslavement of Europe, the total obliteration of the eastern cities such as Moscow, Leningrad and Warsaw, reduction of the Slavs and other Untermenschen to slave labor, transfer of the industries of Eastern Europe to Germany, leaving East Europeans to raise food for the Third Reich. All this was to be Judenrein, Jew-free.

SS members were central players in this -- the Waffen-SS to help conquer those who stood in the path of the "New Order," the Allegemeine, or general SS, and the Gestapo (Geheimes Staatspolizeiamt) to police it.

As did their fuehrer, the SS came to an inglorious end. On April 28, 1945, 10 days before final surrender, Himmler offered Germany's capitulation to the Allies and Hitler was furious. He considered all SS men traitors.

Many senior SS officials tried to escape. Many were caught and some, including Himmler, committed suicide in captivity. Some managed to escape but many were tried and executed or given prison sentences for war crimes.

Many regretted the Third Reich's defeat. And many, belatedly, began to to suffer from an ailment that seemed to bother few during the glory days of the Third Reich: pangs of conscience.