'Altona' (i) was the German seizure of Arendal on the south-eastern coast of Norway within the context of 'Weserübung Süd' (9 April 1940).

Located on the south-eastern coast of Norway between Oslo and Kristiansand, Arendal was a small but important objective for General Nikolaus von Falkenhorst’s Gruppe XXI in its seizure of southern Norway. The primary task of the assault was to seize and sever the undersea telegraph cable between Arendal and the UK.

In the plans for the invasion of Norway presented to Adolf Hitler on 29 February 1940 by von Falkenhorst, Arendal was one of the Norwegian towns and cities earmarked for capture in the initial invasion wave. Like the port town of Egersund, which was also to be seized, Arendal had a land station for one of the two undersea telegraph cables between Norway and the UK, which the Germans deemed it essential to cut while, at the same time, they secured the Norwegian ends of the telegraph cables to Denmark and Cuxhaven in Germany. Arendal was also important as a telegraph junction for the southern parts of Norway, with German personnel tasked to listen in on Norwegian communications. Isolating Norway from the outside world was an important part of the German effort at pacifying the Norwegian population and discouraging resistance to the occupation.

The task of seizing Arendal was allocated to Gruppe IV of the German invasion fleet as an objective second only to Kristiansand, the main port of southern Norway. For 'Altona' one torpedo boat, Greif, was detached from the task force on 8 April, the ships of Gruppe IV having departed the German port of Wesermünde at 05.00 on the same day. Before detaching for her own mission, Greif had been escorting the S-boote tender Tsingtau in her movement to the north off the western coast of Denmark.

In Arendal itself there was considerable concern, largely as a result of the sinking of the German transport Rio de Janeiro, another part of 'Weserübung Süd', off the nearby port of Lillesand earlier in the same day. On her way to Bergen with 313 Luftwaffe personnel and anti-aircraft guns, Rio de Janeiro had been intercepted and torpedoed off Lillesand by the Polish submarine Orzeł. Twelve Germans wounded in this episode were admitted for treatment in Arendal.

The German force for the seizure and occupation of Arendal comprised the 90 bicycle-equipped men of Rittmeister Smith von Wesentahl’s 234^th Staffel of Generalmajor Erwin Engelbrecht’s 163^rd Division, together with an attached unit of 10 signals personnel to operate the town’s telegraph station and sever the telegraph cable to the UK.

The landing force was transported to Arendal by the torpedo boat Greif, commanded by Kapitänleutnant Wilhelm-Nikolaus Freiherr von Lyncker and carrying the torpedo boat flotilla commander Korvettenkapitän Wolf Henne. Once the army troops were on shore and in control of the town, Greif was to depart and rejoin the rest of Gruppe IV at Kristiansand. The Germans expected no resistance as Arendal was unprotected and lacked any garrison.

The sole Norwegian armed unit in Arendal was the small and elderly 70-ton torpedo boat Jo, commanded by Lieutenant Thore Holthe. After receiving reports of German ships off Denmark and at the entrance to the Oslofjord, Holthe had put his 18-man crew on increased readiness and brought up ammunition for the vessel’s two 37-mm guns and single 7.92-mm (0.312-in) machine gun.

Norwegian mobilisation plans had included a company of infantry for local defence, but as no mobilisation orders had been issued before the start of the German attack, the town was undefended on its landward side.

As Greif moved toward Arendal, the vessel encountered thick fog, forcing von Lyncker to decrease speed and thereby delaying the arrival at Arendal. According to the operational plans for the invasion, all the German landing groups were to arrive at their targets simultaneously at 04.15, but Greif reached Arendal only at 08.20. At 01.00, with the vessel still more than seven hours from Arendal, the Germans had received radio reports of fighting taking place in the Oslofjord, and all the lighthouses along the south coast of Norway between Marstein in the west to the Swedish border in the east, had been extinguished during the previous evening, on the orders of Admiral Henry Diesen, commander of the Norwegian navy. Although Greif was spotted by customs personnel as she made her way through the narrows leading to the town, the reports of the intruding warship did not reach Holthe on board Jo.

As she entered the Arendal harbour at 08.30, Greif was spotted from Jo, which was preparing to depart for Lyngør to join two other torpedo boats, Grib and Ravn. The Norwegian neutrality regulations ordained that as Arendal was not a protected war port, Holthe was required to have orders before opening fire at any intruder. As he had no orders or information to act on, and Jo was in an unfavourable position to attack, the torpedo tubes of the moored naval vessel pointing inland, Holthe did not open fire.

Greif reached the quay without encountering resistance other than a few rounds of rifle fire from a customs officer and his son. The 100-strong landing force quickly disembarked and occupied the town, and by 09.00, Greif was departing for Kristiansand. During the short time the German torpedo boat spent in Arendal, Holthe had considered carrying out an attack, but decided not to do so as the German ship was overwhelmingly superior in firepower and there were large numbers of civilians on the quay area. As Greif was about to depart Arendal, a Norwegian Marinens Flyvebaatfabrikk M.F.11 seaplane, one of four that had escaped from Kristiansand before the German attack on that city, alighted next to Greif. Before the Germans could react, however, the crew of the Norwegian seaplane realised that Arendal had been captured, and took off and, chased with anti-aircraft fire, flew south to the nearby unoccupied village of Fevik.

The bicycle-mounted German infantry seized control of the town’s railway station, post office, police station and telegraph building. The undersea cable to the UK which, unknown to the Germans, had been inoperable for more than three months, was severed. As they took control of the town without encountering any opposition, the Germans also seized a cache of rifles which had been used by the Norwegian authorities to provide military training to civilian volunteers in the months leading up to the invasion.[11] Before the Germans reached the Norwegian army’s air raid station and the Norwegian navy’s group centre in Arendal, the administrative officers there had made their way out of the town.

After Greif had left Arendal, Holthe took Jo out of the harbour and set up an ambush east of the town in case the German warship came back in that direction, but later in the day steamed his vessel to Lyngør to link with Grib and Ravn. The three torpedo boats spent the next eight days trying to support the Norwegian land forces being mobilised in Telemark county, surviving several air attacks during the time. After considering evacuating the torpedo boats to the UK and then dismissing the idea as impractical, Holthe and the other commanders scuttled their vessels off Lyngør on 17 April. The crews went home and the ship commanders tried to join Norwegian forces in western Norway.

Although the population of Arendal had reacted calmly to the German invasion, rumours soon began to circulate about a supposed Allied bombing raid scheduled for 12.00 on 10 April and most of the population fled the town in the early hours of 10 April. There was no British air attack, but it was several days before the majority of the civilians returned. The German landing force was billeted in a school building, and von Wesentahl arranged meetings with the local Norwegian authorities to ensure their co-operation in accordance with the rules of occupation. Arendal’s mayor agreed to help maintain calm in the town.

On 14 April several of Arendal’s citizens founded the Arendal Group, which had since been regarded as the first organised resistance group in occupied Norway during World War II. Comprising for the most part men employed in the shipping industry, the group initially provided supplies to the Norwegian forces fighting at Vinje in Telemark. After the fighting at Vinje had ended on 5 May, the group continued its activities with intelligence work until discovered by the Gestapo on 14 August, after which almost 100 people were arrested.

Another southern Norwegian town occupied on 9 April was Egersund, between Stavanger and Kristiansand. The Germans considered the town a worthwhile target as it was the location of the land station for an undersea telegraph cable from Norway to Peterhead, Scotland. By severing Norway’s links with the outside world, the Germans believed that they could slow the news of 'Weserübung' from reaching the outside world. The seizure would also aid the Germans in gaining control of Norway’s communications, and in using those communications to pacify the population and discourage resistance, and the Germans also feared that the good harbour at Egersund, if left unoccupied, could be used for Norwegian or Allied troops to attack Stavanger’s airport at Sola, whose facilities featured prominently in the German invasion plan and were earmarked for seizure in 'Stadthagen'.

The town was to be seized by Gruppe VI, the smallest of the six German invasion forces. Assembled at Cuxhaven, the four minesweepers of Gruppe VI, under the command of Korvettenkapitän Kurt Thoma, departed for Norway at 05.45 on 8 April and, on their way north, accompanied the minesweepers and minelayers of two of the four Gruppen involved in the seizure of Denmark. Off the coast of Denmark, the ships of Gruppe VI separated and continued toward Norway in heavy wind and poor visibility. By the early hours of 9 April, the vessels of Gruppe VI had lost contact with each other, with M 1 and M 9 managing to stay together in the fog and push on in the direction of Egersund.

Gruppe VI's vessels had embarked 150 soldiers of the bicycle squadron of Rittmeister Friedrich Eickhorn’s 169^th Aufklärungsabteilung of Generalmajor Hermann Tittel’s 69^th Division. The bicycle unit had been transported by train from its base in Stettin to the port of Cuxhaven on 7 April 1940.

Based at Egersund was the elderly 84-ton torpedo boat Skarv, and the modern destroyer Gyller, though the latter was absent on an escort mission to Kristiansand. On 8 April Skarv had been ordered to a state of increased readiness under the command of Sub-Leutenant Hjalmar Svae, who had asked for permission.

Like Arendal, Egersund was not a garrison town and therefore had no permanent army presence, but on 8 April 1940 a 36-man Jeger platoon under the command of Captain Carsten Dehli had been instructed to move into the town. The unit relocated by train from the army camp at Madlamoen late in the evening of 8 April.

At about 04.00 on 9 April, M 1 and M 9 came within sight of Egersund, and while the latter remained off the port to secure the surrounding waters, the more manoeuvrable M 1, carrying Eickhorn and 40 troops, entered Egersund harbour. At 04.15 the Germans landed near the moored Skarv, the guard on board the Norwegian vessel initially believing M 1 to be Gyller returning from Kristiansand. The Germans quickly boarded and took control of the torpedo boat, though the Norwegian crew did manage to destroy maps and important documents, as well as making a telephone call to the regional naval headquarters in Kristiansand.

With the harbour area of Egersund under German control, M 1 replaced M 9 off the port, allowing the latter to land her embarked troops. While 12 soldiers remained on guard in the harbour, the rest of the German troops spread out through the town, seizing pre-selected targets. The telephone and post office, the police station and the railway station were occupied, and the entrance to the harbour put under guard.

Shortly after reporting to his superiors in Stavanger that a 'large' force had landed in Egersund, Dehli and his men were surprised and captured in their quarters and observation posts. The naval personnel seized in the initial phase of the landing were later moved to the building where the army men were held.

The formal surrender of Skarv took place later in the day.

An hour after the capture of Egersund, the delayed M 2 and M 13 arrived, and after all the troops and their equipment and supplies had been landed, the four minesweepers departed to return to Kiel in northern Germany. Some time after departing Egersund, however, the force was ordered to divert to Kristiansand in order to support the 'Karlshafen' operation. The German forces attacking Kristiansand had encountered unexpectedly heavy resistance, but the southern port city was secured before the Gruppe VI minesweepers arrived during the afternoon of 9 April.

After the capture of Egersund, Eckhorn initially placed the telegraph cable to Scotland under armed guard but later cut the link in compliance with his orders. The German beach-head at Egersund was initially isolated from other German forces as a result of defective radio equipment and successful Norwegian efforts to cut the telephone lines in the area. Contact with the German units at Stavanger was eventually achieved by despatching on a motorcycle an officer disguised as a civilian.

Dehli’s inaccurate report on the size of the German force in Egersund led the commander of the Norwegian forces in Stavanger, Colonel Gunnar Spørck, to withdraw his forces from the Stavanger coastal area of Rogaland county and set up defensive positions farther inland. This unforced Norwegian retreat allowed the Germans to build up forces and make use of Sola airport as a base for the Luftwaffe, and from here German bombers dominated the waters of the Skagerrak and the eastern parts of the North Sea.

After heavy fighting in the Dirdal area from 15 April onwards, the Norwegian forces in the region capitulated in late April 1940.

Some citizens of Egersund left the town soon after the German landing to join the Norwegian units being formed to defend against the invasion, and the German unit which had captured Egersund saw action against Norwegian forces from mid-April onward.

After capturing Egersund, Eckhorn set about enforcing German rule in the town. Cars and lorries were confiscated for use by the German armed forces, the local press was ordered to follow the instructions of the invaders and print German propaganda, and a black-out was introduced. Though Egersund’s civil population at first reacted calmly to the German invasion, on 10 April panic broke out in the town after unfounded rumours held that 600 British bombers were about to attack. Despite the efforts of the Germans and municipal officials to restore order, almost all of the population fled to the countryside within the hour, leaving only Germans and some municipal workers in the town. Similar incidents of popular panic based on rumours occurred in other Norwegian town and cities on 10 April, most prominently in Oslo, the capital.

The prisoners the Germans took in Egersund were set to construction work on the air base at Forus in Stavanger, before being released in June 1940, and Skarv was pressed into German naval service as Gazelle, and was lost in a collision during 1942.