This is the second in a series comparing two incidents from World War II in which ships tried to force entry into a hostile harbor. Part one looked at the bloody, but ultimately successful British assault on the fortified port of St Nazaire. This part will look a German attempt to force their way into Oslo, Battle of Drøbak Sound. Part three considers what these incidents can tell us about what it takes to stop a terrorist attack on an American port using a ship as a weapon.

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Early in World War II, After the invasion of Poland, but before the invasion of France, the Germans invaded Norway to secure their access to Swedish steel and Iron ore and deny it to the British. (Denmark was also invaded on the same day, to secure airfields to support the Norway invasion.) Unlike their other invasions, there was no direct land route into Norway, so the invasion had to came by sea. With the Royal Navy and their French ally dominate at sea, the transit would be risky, but resistance from the Norwegians was expected to be light. Norway was at peace. They had only a small Navy and standing Army. Their defense depended primarily on mobilizing reservists. If they could be defeated before they mobilized, it would be a quick and relatively inexpensive campaign.

Six separate task forces would seize critical facilities all along the Norwegian coast. Rather than a Normandy style assault, the invasion of Norway looked like several simultaneous Special Forces operations. Troops would be landed from warships that could make the transit quickly. It would all be over before the Norwegian military could react–or so they thought.

The Target:

The particular operation we will examine was to seize the seat of power in Norway. It was intended to capture the capital, Oslo, and with it, the King, the Norwegian cabinet, the Storting (Norwegian Parliament) and the national gold reserve.

The Defense:

In southern Norway, due north of the Denmark, Oslo lies about 53 nautical miles up the Oslo Fjord. About 35 miles up the fjord is a restriction, an island narrows the fjord. At the narrowest point it is only 600 yards from the island to the far shore. On this island, occupying the south end, they placed the Oscarsborg Fortress.

Oscarsborg Fortress was completed forty years before the assault in 1901.
Main Battery:
3 × 28 cm (11″) coastal guns (255 kilo/561 pound projectiles) installed in 1893 (Made in Germany by Krupp, they were named Moses, Aaron and Josva)
4 × anti-aircraft machine guns
Kopås Battery:
3 × 15 cm (5.9″) coastal guns located on the opposite shore.
Husvik Battery:
2 × 57 mm (2.25″) mine barrier protection guns
Torpedo Battery:
3 × double land based underwater launch tunnels for 45 cm (17.7″) torpedoes. These torpedoes, made in Austria-Hungary 40 years before, in what is now Croatia, were considerably smaller than most world war II torpedoes, which were 53 cm (21″) in diameter.
Seiersten Battery:
2 × Bofors 40 (1.6″) mm L/60
anti-aircraft guns
3 × Colt M/29 7,92 (.30 cal) mm anti-aircraft machine guns
Håøya Battery:
4 × Colt M/29 7,92 mm anti-aircraft machine guns
Nesset Battery:
4 × 57 mm Cockerill L/60 guns
Infantry support:
One company of the
Norwegian Royal Guards
Total crew:
45 officers
293 NCOs and men,
69 officers and men of the Norwegian Royal Guards

“Apart from the officers and NCOs, almost all soldiers manning the fortress were fresh recruits, having only been conscripted seven days before, on 2 April. Because of the influx of four hundred and fifty fresh recruits, the fortress’ naval mines were not deployed on 9 April. Part of the recruits’ training was to lay the mine barrier, a process planned for a few days later.”

Excellent pictures of the fortress, its weapons, and the scene of the engagement are here.

The Attacking Force:

The German assault force included the heavy cruiser Blücher (at 14,247 tons standard and 18,208 tons full load (fl), she and her sisters were the largest heavy cruisers in the world), heavy cruiser Lützow (formerly Deutschland, commonly referred to as a pocket battleship, 16,200 tons full load), light cruiser Emden, (7,100 tons) with three torpedo boats (small destroyers, 1,300 tons) and eight small minesweepers (R-boats, 160 tons). In addition to the ships’ crews, about 2,000 soldiers and other “passengers” were embarked on the ships.

In the lead was the Blücher, only a little more than six months old. In addition to her crew, Blücher “carried 882 ‘passengers’: Generalmajor Erwin Engelbrecht and his staff of officers; soldiers to occupy Oslo; bureaucrats and officials for taking over the administration of the capital and with it most of the central institutions of the country (as well as, importantly, the print and broadcast media); and a military band.”

Timeline:

8 April 1940, Just before midnight, Pol III, 214 tons, originally a whaler, guarding the inlet to Oslofjord observed suspicious vessels. She alerted the Norwegian defenses. An invasion was in progress, but it was not yet clear by whom.

In spite of the odds, the little ship attacked. “After firing a warning shot, Pol III closed with the German torpedo boat Albatros. Realising that the enemy would not turn away, but was going to violate Norwegian neutrality, Pol III fired flares to alert Norwegian coastal batteries and rammed the Albatros in the side. From the Albatros it was clear that the guns on Pol III were manned, and that the Norwegians intended to fight. The Albatros hit the small Norwegian vessel with anti-aircraft fire, wounding the captain, Leif Welding-Olsen, and starting several fires. As Pol III was burning, her crew abandoned the vessel and was captured. Leif Welding-Olsen, weakened by blood loss, did not manage to enter the lifeboat and drowned, becoming the first Norwegian fatality in open war between Norway and Nazi Germany.”

Later the attackers passed Oslo Fjord Fortress. Warning shots were fired, but the ships sailed on unharmed.

Approaching Drøbak and the Oscarsborg Fortress, the attacking force was only making seven knots because of darkness and restricted waters. (These were the days before radar.)

9 April, 04:21 The fortress’ guns opened fire on Blücher. The fortress had only one crew for the heavy guns, but by splitting the gun crew they were minimally able to man two. The loading was laborious and consequently only one round was fired from each of the two guns that were manned. The third gun, while loaded was not fired. The defenders held their fire until the warships were at point-blank range (most sources state that fire was opened at a range of 1,600 to 1,800 meters (about one mile).

The first round hit amidships, near the base of the main mast, penetrating a magazine where weapons for the ship’s scout plane were stored, blowing out bulkheads and starting an intense fire. The second round hit a forward 8″ gun turret, blowing parts of it over the side and knocking out all power to the main guns.

Thirteen 15 cm rounds and 30 57 mm rounds hit the cruiser. A 15 cm round from the Kopås battery disabled the Blücher’s steering system and forced the cruiser’s crew to steer by engines to avoid running aground. Shell fragments disabled the firefighting system.

The cruiser passed beyond the reach of the guns. As she passed the fortress the Norwegian defenders could hear the crew singing Deutschland, Deutschland über alles. At this point, the Captain of the cruiser still thought he might save his ship.

04:30 The fortress launched its secret weapon, two 40 year old torpedoes at a range of only 500 meters. The first struck forward, below the first 8″ turret. It did not seem to cause much damage, but the second hit in the engine spaces, bringing her to a stop.

Next in line, Lützow was hit three times by the Kopaas battery’s 5.9″ guns, temporarily disabling both her 11″ turrets. Believing that the Blücher had stumbled into a minefield, Lützow and the remaining German ships withdrew.

05:30 Blücher’s midships AAW ammunition magazine exploded, rupturing fuel tanks and adding to the inferno.

06:00 The order was given to abandon ship.

06.22 Blücher capsized and sank by the bow. Of the 2,202 on board, some 830 died (at least 320 of them crewmen).

The remaining ships offloaded their troops below the fort. Resistance within the city was quickly overwhelmed, but the delay made it possible for both Norway’s gold and her government to escape. The Norwegian government was able to continue the defense of Norway until it was forced to  evacuate to the UK on 7 June. The Norwegian Army in Norway surrendered on 10 June, but the government in exile continued the fight.

Addendum:

As Lützow was returning to Germany, she was torpedoed by submarine HMS Spearfish on 11 April. One of a spread of four torpedoes hit the Lützow in the stern, destroying her propellers and rudder, fracturing the hull and leaving her dead in the water and sinking slowly. Tugs reached her a day later and under tow she eventually reached Kiel naval repair yard on 14 April.

In the photo you can see her fractured hull, the stern drooping and partially submerged, the two quadruple torpedo tubes have already been removed from the circular foundations.

After being repaired, while enroute  Norway, on 13 June, 1941 she was again torpedoed, this time in the engine spaces by an RAF Beaufort twin engine fighter bomber. Hit on the port side she took a 21 degree list. All eight of her main diesels engines were dislodged. Once again Lützow was dead in the water and without power. She would be out of service for another eleven months. The rest of her career was little more successful being sunk in shallow water in port, raised by the Soviets after the war, and then scuttled in 1947.

And little Pol III, she survived her encounter, served out the war in German service in Norway, helped to clear mines after the war, and apparently is still working as a fish transport.

(All sources were on line and are linked.)