'Eclipse' (iv) was the Allied overall designation of the plans drawn up or considered for the treatment of Germany after the end of the war (spring 1945).

As the end of the war in Europe approached, the Western Allies and the USSR agreed that, before their armies started to converge, there was a clear need for clear rules of engagement so that accidental clashes could be avoided. The 'Eclipse' (iv) plan therefore established zones of occupation and lines of demarcation, and these were later approved at the 'Argonaut' conference at Yalta during February 1945. The lines of demarcation extended from Lübeck on Germany’s Baltic coast to the German/Swiss frontier, and placed Denmark and its islands firmly in the Western Allies' sector.

From Swedish government sources, however, the Western Allies received intelligence that the Soviets intended to disregard the Yalta agreement in some places to secure important strategic advantages. For example, the Soviets had ordered General Leytenant Aleksei P. Panfilov’s III Guards Tank Corps of Marshal Sovetskogo Soyuza Konstantin K. Rokossovsky’s 2^nd Belorussian Front, which was advancing to the west through the northern coastal region of Germany, to pierce the Yalta line at Lübeck and drive a corridor through Kiel and Flensburg to secure and hold Denmark, thereby providing the USSR with an ice-free harbour and an outlet to the North Sea.

Although not mentioned in the intercepted signal traffic, the Soviets would certainly have had to hold Kiel and Schleswig-Holstein to provide the road and rail access required for the maintenance of a fleet based in ex-Danish ports.

For obvious strategic and political reasons, the Allies could not countenance any such Soviet development, but at the same time wished to avoid a military clash with the Soviets. To block the Soviet move on Denmark, therefore, the Allies made three immediate moves.

A British naval force under the command of Captain H. W. Williams and comprising the light cruiser Birmingham, anti-aircraft cruiser Dido, modern destroyers Zealous, Zephyr, Zest and Zodiac, and a minesweeper flotilla, was to sail immediately to Copenhagen, ostensibly to accept the German surrender but also to act as a deterrent should the Soviets try to reach the Danish capital by sea. At the same time two RAF squadrons of rocket-firing Hawker Typhoon single-engined fighter-bombers to stand by to land on emergency airfields near Copenhagen as the naval flotilla arrived. When the airfields had been secured, the headquarters and defence company of Brigadier G. W. Lathbury’s British 1^st Parachute Brigade was to be flown in to take the surrender of the German troops in Denmark and also serve as a further deterrent to any Soviet enterprise.

On 4 May the minesweeping flotilla cleared mines in the Skaggerak and Kattegat and led the cruisers Birmingham and Dido, accompanied by the four destroyers, into Copenhagen harbour, where the German heavy cruiser Prinz Eugen and light cruiser Nürnberg surrendered. The first Typhoon squadron landed on an airfield outside Copenhagen on the same day, and the second arrived on 6 May.

Farther afield, a so-called 'T' Force (two companies of 5^th King’s Regiment, 30^th Assault Unit, Royal Navy and 50 scientists and specialists), totalling about 550 men, was to advance immediately to take and hold Kiel. It was also to deploy covering troops to secure the targets of 'T' Force over a distance of 160 miles (255 km) between Kiel in Germany and Aarhus in Denmark, and 'to complete this operation before the Russians get there'. When the relevant order was given, on 1 May, Kiel was 50 miles (80 km) beyond the front line and the Germans were still resisting.

'T' Force had been formed to operate immediately behind or with front-line troops to acquire and protect sensitive intelligence targets, so this commando-type operation was not an operation of the kind for which it had been formed, equipped and trained. Moreover, there was no intelligence about Soviet intentions. 'T' Force therefore presumed that the Soviets might attempt seaborne raids to acquire some of the force’s objectives, but also was not informed that it might be required to undertake the impossible task of stopping two Soviet tank divisions.

The key to the British plan was to halt the Soviet forces at Wismar, some 50 miles (80 km) to the east of Lübeck. If Lübeck could be secured before the Soviets arrived, Denmark would be safe, but if not the forces sent to Kiel and Denmark would be too little and too late, and both Denmark and Schleswig-Holstein might therefore become part of the Soviet empire.

The Allied formation nearest to Wismar was Major General E. L. Bols’s British 6^th Airborne Division, which had just completed an assault crossing of the Elbe river at Lauenburg, 50 miles (80 km) to the south-west of Wismar. At 18.00 on 29 April Bols received urgent verbal orders to advance immediately, and take and hold Wismar, 'before the Russians get there and to stop them advancing to Lübeck'.

For this operation Bols had the 3^rd Parachute Brigade and was allocated an escort of one squadron of the Royal Scots Greys, the divisional artillery, and transport for his lightly armed airborne troops. It took 14 hours for Bols to assemble this 'Wismar' Force on its start line and begin its advance.

At 18.00 on 5 May representatives of Germany’s new leader, Grossadmiral Karl Dönitz, had met Montgomery at Lüneburg Heath and signed a ceasefire and the surrender of all the German forces in north-western Germany, the Netherlands and Denmark, effective from 08.00 on the following day.

The infantry of 'T' Force and the 30^th AU secured their designated Danish targets on 5 May, and on the next day 'T' Force secured major targets in Aarhus and Kolding, and one company of Brigadier J. H. N. Poett’s 5^th Parachute Brigade secured Copenhagen airport for the arrival of the first elements of the 1^st Parachute Brigade, which landed on 7 May to organise the surrender of German troops in Denmark.

In the Schleswig-Holstein part of the undertaking, on 1 May the commander of 'T' Force received the order to advance, take Kiel and secure the 'T' Force targets before arrival of any Soviet forces as soon as covering troops and specialist elements were available for operation. On 4 May the surrender of Hamburg was completed, and at 18.00 on the same day two companies of 5^th King’s Regiment, 30^th AU and 'T' Force assessors arrived Hamburg to form 'T' Force-Kiel, but the local corps commander refused permission for the advance on Kiel to start until 08.00 on the next day.

However, at 03.00 the 'T' Force-Kiel commander got his unit under way, overriding the corps commander on the grounds that intelligence revealed that the road to Kiel would be blocked by the convergence of two Waffen-SS divisions unless 'T' Force-Kiel moved immediately, and that an order from SHAEF overrode an order from the corps in an emergency. At 10.00 on 5 May 'T' Force reached Kiel, passing between the Waffen-SS divisions with an hour to spare. Two companies of the 5^th King’s deployed in Kiel to establish a headquarters and acquire designated targets. The 30^th AU deployed to Flensburg and Danish targets.

At this moment 'T' Force-Kiel comprised about 350 lightly armed troops with a number of unarmed scientists and investigators. They were isolated in a small enclave surrounded by 50,000 members of the German armed forces, some of whose units were still resisting. In the region there were also about 420,000 foreign slave workers, whose only wish was to start of their way home as soon as possible.

At 10.20 the commander of 'T' Force-Kiel set up his headquarters in the Kiel naval headquarters and issued a communiqué which was accepted by Dönitz: this ordered all members of the German armed forces to return to and remain in their barracks or present accommodation, no ships in Kiel to leave harbour or enter the Kiel Canal, all keys to be handed over, no documents to be destroyed, and all weapons (except those for sentries on duty) to be handed over.

At 10.50 the local police chief reported to the commander of 'T' Force-Kiel and was ordered to issue to all foreign workers a proclamation urging patience and stating that the German police were allowed to retain side arms to maintain order, the British intended to return all workers to their homelands as quickly as possible, all foreign workers were to remain in their homes or localities and not move until so ordered, roads were to be kept clear, and any attempt to begin the homeward journey would cause delays and make it impossible for the British to provide food.

On 6 May 'T' Force deployed one company of the 5^th King’s to Kolding and Aarhus in Denmark, and one company of the 5^th Parachute Brigade passed through Kiel on its way to Copenhagen airport. On 8 May Major Brian Urquhart, the brigade major of 'T' Force, arrived in Kiel at 11.00 with orders from Lieutenant General E. H. Barker, commander of the British VIII Corps, to place the commander of 'T' Force-Kiel under arrest for deliberately disobeying Barker’s order not to advance, and to keep him under arrest until Barker arrived on the following day. Barker arrived and then released the commander of 'T' Force-Kiel after learning of the overriding order to meet the Soviet threat.

In the Wismar area, at 08.00 on 1 May Brigadier S. J. L. Hill, commanding the 3^rd Parachute Brigade, received verbal orders to advance immediately from Lauenburg to Wismar, 50 miles (80 km) to the north-east on the Baltic coast. (Under the terms of the Yalta agreement the Soviets were permitted to press their advance another 50 miles [80 km] to the west, but Hill was given no explanation.) The 3^rd Parachute Brigade had to force its way through vast numbers of refugees fleeing the Soviets, and the Germans were still fighting.

The speed of the 3^rd Parachute Brigade’s advance took the Germans by surprise, however, and where there was resistance, often in the form of road blocks, the tanks of the Royal Scots Greys shot their way through. At 09.00 on 2 May the 3^rd Parachute Brigade’s advance guard, the Canadian 1^st Parachute Battalion, entered Wismar and cleared town with help of the tanks after a fighting advance of 50 miles (80 km) in 25 hours, much of it by night. By 12.00 the rest of the 3^rd Parachute Brigade had arrived and set up a defensive position facing to the east. The 3^rd Parachute Brigade was the first British unit to link with the advancing Soviet 70^th Army of General Polkovnik Vasili S. Popov.