'Greif' (iv) was a German special forces 'false flag' operation within 'Wacht am Rhein' by men of SS-Obersturmbannführer Otto Skorzeny’s 150^th Panzerbrigade (otherwise 150^th SS Panzerbrigade), dressed in US uniforms and travelling in US vehicles, to disrupt the US rear areas and so prevent reinforcements and supplies reaching the units of Lieutenant General Courtney H. Hodges' US 1^st Army most in need of them (16 December/late December 1944).

The operation was the brainchild of Adolf Hitler and designed to ensure the capture or one or more of the bridges over the Meuse river before they could be destroyed. German soldiers, wearing captured British and US uniforms, and travelling in captured Allied vehicles, were thus to cause confusion in the rear of the Allied lines and pave the way for what Hitler expected to be an advance to Brussels and Antwerp. This would have severed General H. D. G. Crerar’s Canadian 1^st Army, Lieutenant General Sir Miles Dempsey’s British 2^nd Army and Lieutenant General Courtney H. Hodges’s US 1^st Army of Field Marshal Sir Bernard Montgomery’s Allied 21^st Army Group from the rest of the Allied armies in north-west Europe, which would also be denied the use of the great port of Antwerp to meet the bulk of its logistical needs.

A lack of vehicles, uniforms and equipment limited the size and scale of 'Greif' (iv), which did not achieve its original aim of securing the Meuse river bridges.

Skorzeny had come into great favour with Hitler following the success of the 'Eiche' rescue of the Italian leader Benito Mussolini following his overthrow and incarceration, and 'Panzerfaust' kidnap of the son of the Hungarian regent, Vezérfökapitány Miklós Horthy de Nagybánya, to force Horthy’s resignation and keep Hungary from defecting to the Allied camp. Following his return to Germany, Skorzeny was summoned to meet Hitler at his headquarters at Rastenburg in East Prussia on 22 October 1944. After congratulating Skorzeny and announcing that he had been promoted to SS-Obersturmbannführer (lieutenant colonel), Hitler outlined the planned 'Wacht am Rhein' offensive in the Ardennes and the role Skorzeny was to play in this.

Skorzeny was to form the special 150^th Panzerbrigade, whose purpose would be to capture one or more of the bridges over the Meuse river before they could be destroyed. Hitler informed Skorzeny that he had decided this could be accomplished more quickly and with fewer losses if Skorzeny and his men wore US uniforms. Hitler also remarked that small units disguised in enemy uniforms could cause great confusion among the enemy by giving false orders, upsetting communications, and misdirecting troops.

Skorzeny was well aware that the Hague Convention of 1907 meant that any of his men captured while wearing US uniforms could be executed as spies, and this was a possibility which also caused much discussion with Generaloberst Alfred Jodl, the chief of the operations staff of the Oberkommando der Wehrmacht, and Generalfeldmarschall Gerd von Rundstedt, the Oberbefehlshaber 'West'.

The schedule already fixed for 'Wacht am Rhein' left Skorzeny with only five or possibly six weeks in which to recruit and train his new unit for what Hitler named 'Greif' (iv). Within four days Skorzeny had sent his plans for the 150^th Panzerbrigade Jodl and, despite his demand for 3,300 men, was immediately authorised to proceed and promised full support. On 25 October the Oberkommando der Wehrmacht issued a request for men possessing a 'knowledge of the English language and also the American dialect'. This request was passed on to every headquarters on the Western Front, and soon became known to the Allies.

The new unit also needed US vehicles, weapons and uniforms, and the forces under von Rundstedt’s command were asked to find 15 tanks, 20 armoured cars, 20 self-propelled guns, 100 Jeeps, 40 motorcycles, 120 trucks, and British and US army uniforms, all to be delivered to the new brigade’s training camp at Grafenwöhr in eastern Bavaria. The equipment actually located and delivered fell far short of Skorzeny’s requirements, and included just two Sherman medium tanks in poor condition. Skorzeny therefore had to use German substitutes, including five PzKpfw V Panther tanks and six armoured cars. The brigade was also flooded with Polish and Soviet equipment sent by units which had no idea for what the equipment was needed. So far as English-speakers were concerned, only 10 men who spoke perfect English and had some knowledge of US idiom were located, 30 to 40 men who spoke English well but had no knowledge of US slang, 120 to 150 men who spoke English moderately well, and about 200 men who had learned English at school.

Faced with these setbacks, Skorzeny trimmed the 150^th Panzerbrigade from three to two battalions, and assembled the 150 best English speakers into a commando unit named Einheit 'Stielau'. Skorzeny also recruited a company of the SS-Jagdverband 'Mitte' and two companies of the 600^th SS-Fallschirmjägerabteilung, and was given two Luftwaffe parachute battalions formerly allocated to the Kampfgeschwader 200 special missions wing, crews from Panzer regiments, and gunners from artillery units. Some 2,500 men from all arms of the Wehrmacht (1,000 from the army, 500 from the Waffen-SS, 800 from the air force and 200 from the navy) were finally assembled at Grafenwöhr.

The Allied equipment also assembled was also considerably less than had been anticipated: sufficient US weapons were found to equip only the commando unit, and only four US Army scout cars, 30 Jeeps and 15 trucks were located, the difference being made up with German vehicles painted in US olive drab and carrying Allied markings. Only a single serviceable Sherman tank was available, and the brigade’s Panther tanks were disguised as M10 Wolverine tank destroyers by removing their cupolas and disguising their hulls and turrets with thin sheet metal. The problem of recognition by the Germans' own forces was crucial, and the vehicles were to identify themselves by various methods: the vehicles displaying a small yellow triangle at their rears; the tanks keeping their guns pointing in a particular direction; the crews wearing pink or blue scarves and removing their helmets; and flashes from a blue or red torch at night.

As the brigade prepared for action, there was the inevitable spate of rumours about its task, these rumours including the relief of the besieged towns of Dunkirk in the north-east coast of France or even of far-off Lorient on the west coast of France; the capture of Antwerp; and the seizure of General Dwight D. Eisenhower, the Supreme Allied Command at his SHAEF headquarters in Paris. Only on 10 December did Skorzeny divulge to his subordinate commanders what was afoot: On the northern side of 'Wacht am Rhein', the 150^th Panzerbrigade was to capture intact and then hold at least two of three bridges over the Meuse river at Amay, Huy, and Andenne on the stretch of the river between Liége and Namur. The 150^th Panzerbrigade was to begin its operation when the advance of SS-Oberstgruppenführer und Generaloberst der Waffen-SS Josef Dietrich’s 6^th SS Panzerarmee the high fen area between the Ardennes and the Eifel highlands. The brigade’s Kampfgruppe 'X', Kampfgruppe 'Y' and Kampfgruppe 'Z' would then move toward the three designated bridges.

The Einheit 'Stielau' special commando unit had been assembled from the brigade’s best English speakers, but few of these possessed much if any experience of either clandestine operations or sabotage. There was little time for training, but the men were given short courses in demolition and radio skills, studied the organisation of the US Army and its badges of rank and its drill, and some were even sent to the prisoner of war camps at Küstrin and Limburg to refresh their language skills through contact with US prisoners.

Dressed in US Army uniforms (the highest rank used was that of colonel), armed with US weapons, and travelling in US Jeeps, the commandos were given three missions: firstly, five-or six-man demolition squads were to destroy bridges, ammunition dumps, and fuel stores; secondly, three- or four-man patrols were to reconnoitre each side of the Meuse river and also pass on bogus orders to any US units they met, reverse road signs, remove minefield warnings, and close roads with warnings of non-existent mines; and thirdly, 'lead' commando units would co-operate closely with the conventional attacking formations to disrupt the US chain of command by destroying field telephone wires and radio stations, and issuing false orders.

On 14 December the 150^th Panzerbrigade was assembled near Bad Münstereifel, and in the afternoon of 16 December moved out, advancing behind SS-Brigadeführer und Generalmajor der Waffen SS Wilhelm Mohnke’s 1^st SS Panzerdivision 'Leibstandarte-SS Adolf Hitler', SS-Brigadeführer und Generalmajor der Waffen SS Hugo Kraas’s 12^th SS Panzerdivision 'Hitlerjugend' and Generalleutnant Gerhard Engel’s 12^th Volksgrenadierdivision, with the aim of moving around them when they reached the high fen area.

When the 1^st SS Panzerdivision failed to reach the starting point for 'Greif' (iv) within the planned two days, however, Skorzeny appreciated that his operation’s initial aims were now impossible of attainment. On 17 December, therefore, Skorzeny attended a staff conference at the headquarters of the 6^th SS Panzerarmee and suggested that his brigade be used as a normal unit. This was agreed, and he was ordered to assemble to the south of Malmédy and report to the headquarters of the 1^st SS Panzerdivision in Ligneuville.

On 21 December the 150^th Panzerbrigade tried to take Malmédy, but its several assaults were repulsed by the town’s US defenders. This was the only significant German attempt to take Malmédy during 'Wacht am Rhein'.

According to Skorzeny, during an interview with US Army officers in August 1945 after his surrender, the Einheit 'Stielau' despatched four reconnaissance commando units and two demolition commando units during the first few days of the offensive, and three units went with the 1^st SS Panzerdivision, 12^th SS Panzerdivision and 12^th Volksgrenadierdivision, with another three units accompanying the 150^th Panzerbrigade three groups. Skorzeny reported that one commando team entered Malmédy on 16 December, and another team persuaded a US unit to withdraw from Poteau on the same day. Another team rotated road signs and sent an entire US regiment in the wrong direction.

As a result, US troops began asking other soldiers questions that they felt only Americans could answer correctly and thereby uncover German infiltrators. This practice resulted in one US officer, Brigadier General Bruce C. Clarke, commanding Combat Command B of the 7^th Armored Division, being held at gunpoint for five hours after answering a sport question incorrectly, and a captain spending a week in detention after he was caught wearing German boots. Lieutenant General Omar N. Bradley, commander-in-chief of the US 12^th Amy Group, was repeatedly stopped in his staff car by checkpoint guards who seemed to enjoy asking him such questions.

The US paranoia about Skorzeny’s commandos also contributed to tragic and not uncommon instances of mistaken identity. All over the Ardennes, US soldiers attempted to persuade suspicious US security guards that they were genuine, but on 20 December, two such soldiers were killed by a nervous US military policemen, and two more soldiers were killed and several wounded as late as 2 January 1945 when an armoured task force of the US 6^th Armored Division moving into the Wardin area of Bastogne opened fire on the US 35^th Division in a case of mistaken identity.

In all, 44 German soldiers were sent through the US lines in US uniforms, and all but eight returned. The last men were sent through the lines on 19 December, and after this, with the element of surprise lost, the German commandos reverted to the wearing of German uniforms. It was not an uncommon practice at the time to send camouflaged reconnaissance units behind enemy lines, but because of the immense psychological impact of 'Greif' (iv), every occurrence of this was attributed to Skorzeny’s men. In addition, German infantry often salvaged any items of US Army clothing they found, thus it was not out of the question that regular German troops might be killed or captured wearing items of US uniform.

So great was the confusion caused by 'Greif' (iv) that the US Army saw spies and saboteurs everywhere. Perhaps the greatest panic occurred when a three-man German commando team was captured near Aywaille on 17 December after failing to give the correct password. It was one of these men who gave credence to a rumour that Skorzeny intended to capture Eisenhower and his staff. A document outlining the deception elements of 'Grief' (iv), but not its objectives, had been captured by the US 106^th Division near Heckhuscheid, and because Skorzeny was already well known for rescuing Mussolini, the Americans easily persuaded themselves of this story’s accuracy and Eisenhower spent the Christmas period of 1944 isolated for security reasons.

Upon learning of Eisenhower’s isolation, Montgomery departed in his staff car toward Malmédy unaware of a rumour current in the Ardennes that one of Skorzeny’s commandos looked very similar to the British commander and had identified himself as such at several US checkpoints. When American soldiers halted his car at the first checkpoint, Montgomery told them that he would not put up with such nonsense and ordered the driver to keep going. The guards angrily shot out his tires and dragged Montgomery to a nearby barn, where he was detained for several hours until a British officer known to the Americans vouched for Montgomery.

The three Germans captured on 17 December were tried in a military court, convicted and executed by firing squad on 23 December. Three more Germans were also tried on 23 December and shot on 26 December, seven more men were tried on 26 December and executed on 30 December, and three others were tried on 31 December and executed on 13 January 1945. A last man was tried by a military commission in May 1945 and executed near Braunschweig on 14 June.