The Battle of Drøbak Sound

"Either I will be decorated or I will be court martialed”

When we think about courage in war we tend to think in terms of great victories and decisive battles, but heroism is not contingent on fame or success. The Battle of Drøbak Sound, fought during the German invasion of Norway 83 years ago (Read our earlier article - The German invasion of Norway), is one of many stories that remind us of this truth. This article is dedicated to the outclassed recruits who faced the pride of the Kriegsmarine with obsolete weaponry, and who nevertheless managed to achieve a sort of victory even in the face of inevitable defeat.
 
The story of the battle begins with the German invasion of Denmark and Norway, that started in the early hours of April 9, 1940. The campaign is one of the more often overlooked chapters of World War II, and therefore a brief overview is in order.

The Nordic countries of Sweden, Norway, Denmark and Finland have pursued a policy of neutrality in the years leading up to World War II, a neutrality that Hitler was willing to respect as of mid-1939. This respect, however, did not mean he was not watching the area carefully. German industry was heavily dependent on iron ore imported from northern Sweden; much of that ore was taken by railroad to the Norwegian port of Narvik, which never froze over in the winter, and shipped south from there. Additionally, Hitler knew that Britain would likely blockade Germany’s sea ports once the war started, and that the coastline of a neutral Norway would allow German ships to circumvent such a blockade, since the Royal Navy could not effectively intercept them or mine their routes without violating Norway’s neutrality. Of course, these considerations also meant that securing Norway would be a tempting prospect for Britain, as it would allow the country to cut off the Swedish ore shipments. In fact, Winston Churchill, who was still First Lord of the Admiralty and not yet Prime Minister, argued in favor of mining Norwegian coastal waters for these exact reasons as soon as Britain declared war on Germany in early September.

The situation took another turn on November 30, 1939, when the Soviet Union invaded Finland. The blatant violation of national sovereignty pushed the other Nordic countries, who were afraid they might be next, closer Britain and France – and, in fact, Britain made plans to land troops in Norway and have them travel overland to help Finland against Soviet forces. Germany was still at peace with the Soviet Union at this time and remained neutral in the matter, which distanced the country from Norway even further. Additionally, Hitler was keenly aware that the British troops intended for Finland could also be used to secure iron mines in northern Sweden and cut Germany off of that vital supply. Hitler made the decision to invade Norway in order to secure it, its coastline and the iron ore transport route. As for Denmark, it was simply in the way: German forces in Norway would need supplies and reinforcements, and the easiest way of securing those was to also conquer Denmark, which happened to lie between Germany and Norway.

Oslofjord was poorly defended. There was a weak first line of defense at its mouth, but the strongest and last defense was sited at the body of water called Drøbak Sound: a 19th century fortress named Oscarsborg which spread across two small islands and some of the fjord’s two shores. Its main armament was a trio of 28 cm (11 inch) caliber World War I-era German cannons, supplemented by several smaller guns, all of them similarly obsolete by 1940. The waters were also supposed to be protected by a minefield, but it was not deployed at the time; the enlisted personnel of the fortress consisted entirely of fresh recruits still undergoing training, and laying down the minefield was an exercise scheduled for a few days later. The Germans knew about the number and caliber of the fort’s cannons and considered them no threat. What they didn’t know was that the fort also had a secret weapon: an immobile three-tube torpedo battery that could fire torpedoes across the sound. The system used old Whitehead torpedoes bought from Austria-Hungary in 1900, and while the launch mechanism was tested regularly, there was no telling if the torpedoes themselves even still worked.

While the enlisted men at the fort were young recruits, some of the officers had the opposite problem. The commander, Colonel Birger Kristian Eriksen, was in his 64th year and six months away from retirement. The man in charge of the torpedo battery, Commander Senior Grade (equivalent of a U.S. Navy commander) Andreas Anderssen, was an actual pensioner who had retired thirteen years earlier and lived in the nearby town of Drøbak; Anderssen only returned to service to stand in for the actual battery commander who was away on sick leave.

Further up the fjord, Colonel Eriksen received warning of the hostile fleet, but the ships’ identity was unknown: theoretically, they could just as easily have been a British invasion force as a German one. Additionally, the Norwegian rules of engagement at the time demanded that warning shots be fired before opening fire in anger. Hours after the initial engagement, with the unknown ships approaching Oscarsborg, Eriksen decided that the initial exchange further down south already counted as a warning shot. He knew he was wrong by the rules, but when asked for orders at 4:21 a.m., he declared "Either I will be decorated or I will be court martialled. Fire!"

Carrying out that fire order was harder than giving it. Not only were the guns old, but there weren’t even enough trained artillerymen to operate all three. The few that were present rounded up some trainees to help them and managed to fire off a shot each from two of the guns. The third one remained loaded but unfired.
 
The obsolete guns surpassed all reasonable expectations. The first hit penetrated the side of the Blücher and exploded inside a magazine filled with oil, smoke dispensers, incendiary bombs, depth charges and bombs for the ship’s reconnaissance floatplane. The resulting detonation knocked out bulkheads and spread flaming oil across the ship. The second shell knocked out the ship’s electrical systems, rendering its turrets unable to return fire. The fortress’s batteries of smaller guns also opened up on the cruiser, doing relatively little direct damage but suppressing the crew and preventing them from fighting the fire or effectively attacking the fort.
 
It was shortly after the two crippling hits that the identity of the invading flotilla became known. Norwegian soldiers in the fort could hear the sailors aboard the Blücher defiantly sing the German anthem as the ship limped on up the fjord, drawing up to the hidden torpedo battery at around 4:30.

Anderssen launched the torpedo salvo, and the old torpedoes surpassed expectation just like the guns did. The first shot was a bit rushed and only hit the Blücher near her forward turret, but the second one slammed into the cruiser amidships, causing catastrophic damage. The ship sunk at 6:22 a.m., with hundreds of German sailors either freezing in the water or burned to death by flaming oil. Some one thousand of the Blücher’s 1,400 survivors were captured by Norwegian soldiers and placed under light guard for a while, but the soldiers retreated and let the Germans to their own devices later in the afternoon of the 9th as the German invasion was rapidly changing the situation.

When the Blücher sank, the captain of the Lützow assumed it had run into a minefield and, not wanting expose other ships to the same peril, ordered the flotilla to turn around and retreat, later shelling the fortress from a safe distance. A Norwegian cargo ship hauling paper blundered into the battle at some point. The ship’s captain believed he was witnessing some sort of training exercise and kept his course until the vessel was attacked and set on fire by two German minesweepers.

The unlikely victory at Oscarsborg prevented the Germans from capturing Oslo in the early hours of the invasion, and bought time to get the king, the parliament and the gold reserves to safety. Important as it was, though, the victory was short-lived. The Luftwaffe subjected the fort to heavy bombing over the course of the day, while another German contingent of troops was airlifted into Oslo and captured the city. Cut off from support, Colonel Eriksen surrendered the next morning. Though the defenders of Oscarsborg were ultimately defeated, the story of old men and untrained recruits manning obsolete weapons and standing up to a vastly superior aggressor remains with us as a tale of inspiration.