The Strategic Danish Straits

In two world wars, the Battle of the Atlantic has been narrowly won by the Allies. In the unhappy event of a third Battle of the Atlantic, victory or defeat may well depend on who controls that narrow, shallow, island- dotted sea area which lies between the Baltic and the North Sea, known as the Danish Straits.

The problem itself is simple. The Soviet Baltic Fleet has been variously estimated to number at least ninety, perhaps as many as 130 submarines.[1] Such types in such num­bers denote an offensive mission. As time goes by, some of these submarines will prob­ably be nuclear-powered and missile-equipped. The important question is, can these submarines break out of the Baltic and into the Atlantic in the event of war?

On the answer to this question may depend the outcome of the Battle of the Atlantic, the security of NATO, and whether or not our Atlantic seaboard becomes a missile launching pad for Soviet submarines. The Chief of Naval Operations of the German Federal Navy, Vice Admiral Friedrich Ruge, put the problem this way in a recent article in the U. S. Naval Institute Proceedings: “If these narrows are closed it means that there will be 100 to 150 fewer submarines to sow destruc­tion in the Atlantic. It can be said that a future battle for the Atlantic will be decided 50% in the Danish straits.”

The purpose of this article, therefore, is to focus attention on this extremely vital area, to highlight some of its naval problems, its strengths and weaknesses, and to show how any future Battle of the Atlantic seas may be won or lost here.

Geography

The Danish Straits comprise three general areas, the Skaggerak, the Kattegat, and the island passageways. There are three principal and natural sea passages, all of which are in­ternational waterways; (1) The narrow— only three miles wide at Helsingör—but heavily travelled Sound (Öresund) between the island of Zealand on which Copenhagen is situated and the western coast of Sweden; 2) the Great (Store) Belt, which has a width of eleven miles; and (3) the Little (Lille) Belt. In addition to these three natural exits, there are two other artificial exits—the Kiel Canal leading to the North Sea, and the Soviet lakes and canals leading from Lenin­grad to the White Sea. Via this latter route, ships of up to destroyer size can make the passage, but only in the ice-free months. Dis­counting local traffic and fishing craft, some sixty ships pass through the Öresund daily; via the Store Belt, 35 ships pass every day, and via the Lille Belt, an average of eight ships per day. Since the depth of water is fifteen fathoms or less, the area is ideal for mine warfare.[2] Much of the sea area is hazardous to navigation, being plentifully supplied with sand bars, shoals, and fast cur­rents. While a submerged submarine passage is physically possible, the transit would be difficult, to say the least. In any case, peace­time regulations require that submarines tran­sit on the surface. Also, common sense would accept the probability that any ship passing through such confined waters, either sur­faced or submerged, day and night, foul weather or fair, could not escape modern detection devices.

Soviet bases in the Baltic are many and well dispersed. Pillau (now Baltiysk), Königsberg (now Kaliningrad) and Libau (now Liepaya) are all ice-free. Other Soviet naval bases which are partially ice-bound in winter are Riga, Tallin, and Kronstadt. Added to these are the Polish and East German bases at Gdynia, Swinemünde, and Rügen. The sea distance from bases in the ex-Baltic States to the Danish Straits is approximately 300 miles. The nearest satellite airbase is less than fifty miles away—an eight- or ten-minute journey from take-off for a modern jet travelling low level. A short-range ballistic missile could make the trip in about the same time.

History

A brief history of the Danish Straits will reveal how often the Baltic has been an arena of naval dispute and how control of the Straits has been a major objective in recent conflicts.

The first meaningful domination of the Baltic was by the Hanseatic League. From 1241, when it was founded—originally as an alliance between the free cities of Lübeck and Hamburg—until its decline in the mid-17th century, the Hanse ruled the Baltic.

In following centuries, a three-way contest for the Baltic developed—Scandinavia (pri­marily Sweden), Russia, and Germany. Peter the Great created the Russian Navy with control and expansion in the Baltic as one of his major objectives. Britain, of course, was also vitally concerned in Baltic naval affairs, although indirectly, as indicated by the Battle of Copenhagen in 1801, fought under Lord Nelson’s command.

Coming to modern times, the Danish Straits become critically important com­mencing with World War I. German sub­marines and raiders were laying a heavy burden on the Atlantic sea lanes, and the German High Seas Fleet was awaiting an advantageous moment for engaging the British Grand Fleet.

For these and other reasons, a major ef­fort was begun in 1917-18 to bottle up the U-boats and the German Fleet in their har­bors with extensive minefields. The principal mining efforts were to be made in the North Sea and in the Straits of Dover, although two deep channel minefields were laid in the Kattegat in early 1918.

Under Rear Admiral Joseph Strauss, USN, an American minelaying squadron arrived in the area in May 1918. In the words of Secretary of the Navy, Josephus Daniels, their task was to “shut up the hornets in their nests.”

Admiral Strauss’s squadron, consisting of two converted cruisers and eight converted merchant vessels, laid a total of 56,033 mines in the Northern Barrage across the North Sea in five months time. The Royal Navy laid 15,093 mines. Mine warfare experts now agree, however, that mines of the Northern Barrage did not “seal off the North Sea.” The channel minefields across the Straits of Dover, controlled at each end by the Allies, being much shorter and laid in shallower water, accounted for the destruction of eleven U-boats.

Inside the Baltic, the Russian fleet was generally kept confined within the Gulf of Finland by German Naval Forces. The Russians sortied occasionally on minelaying and minor forays, but on the whole, their Baltic Fleet operations were characterized by timidity and lack of enterprise. It was this fleet, incidentally, which first contracted the Bolshevik fever, which broke out in nearby St. Petersburg and the naval base at Kron­stadt. A British naval force, in fact, attacked Kronstadt in 1919. By 1920, after the Baltic Republics gained their independence, Rus­sia’s Baltic coastline was reduced to less than 100 miles—a strip at the head of the Gulf of Finland.

The results of World War I in the Baltic were these:

(a)      A German determination to freely operate in the Atlantic and the Baltic in any future war. (Before 1939, it was a common German boast that when World War II occurred, they did not intend to be locked within the North Sea as they had been in World War I.)

(b)      A renewed Russian ambition to gain control of the Baltic and the Danish Straits.

Reviewing World War II, it is apparent how eagerly both Germany and Russia sought to control the Baltic and its exits. Ac­cording to the captured documents of the “Fuehrer Conferences on Naval Affairs,” Hitler had decided as early as 1937 to elim­inate Russia as a Baltic power. And accord­ing to Field Marshal Goering’s testimony at the Nuremberg trials, during the talks be­tween Molotov and Hiker in Berlin in 1940, Molotov had informed Hitler that the Soviets wanted the approaches to the Baltic Sea, the Sound (Öresund) between Denmark and Sweden, and the Skaggerak. At a later naval conference concerned with his “Operation Barbarossa” plan of attack on Russia, Hitler stated on 2 January 1941, “It must be re­membered that the main aim is to gain possession of the Baltic Straits and Lenin­grad.”

Nor were the English blind to the coming contest. “If either Russia or Germany were to take possession of these [Baltic] republics,” stated the authors of the Report of the Royal Institute of International Affairs in 1938, “the Baltic Sea would be in danger of be­coming little more than a Baltic lake.” After the outbreak of World War II, Churchill re­vealed his appreciation of the Baltic. “I sought eagerly for a way of attacking Ger­many by Naval means,” he wrote. “First and foremost gleamed the Baltic. The com­mand of the Baltic carried with it possibly decisive gains.”

In actual fact, however, the Germans won the race to control the Danish Straits with their swift, unsuspected, and successful attack on Norway and the submission of Denmark in April 1939. The Nazi blitz had these ob­jectives:

(a)      To open the North Sea and the At­lantic to the German Fleet.

(b)       To sit astride the lines of communica­tion of the Allies and Russia in North Norway.

(c)       To neutralize the British Navy and assist in the destruction of Britain by establishing air and naval bases on the west coast of Norway.

(d)       To secure the vital Swedish iron ore routes.[3]

With the Nazis firmly in control of the Danish Straits, the Soviets were pushed fur­ther back into the Baltic than they had been in World War I. Admiral Isakov in his book The Red Fleet in the Second World War, said that whereas in World War I the Soviet Baltic Fleet held bases on the east and west shores of the Gulf of Finland, in World War II, the Germans held Helsinki and threatened Leningrad. Not until September 1944 did the Red Banner Baltic Fleet succeed in escaping from the Gulf of Finland. In the naval battles of the Baltic, the Reds lost 56 submarines.

From this brief condensation of naval his­tory regarding the Baltic, the Danish Straits, and the Russian Baltic Fleet, these conclu­sions can be reached:

(a)       Except for Sweden, Russian control of the Baltic Sea itself is today virtually complete. Having Russified the Baltic States and neutralized Finland, and holding the Baltic coastlines of Poland and East Germany as satellite posses­sions, the U.S.S.R. is well on its way to achieving Peter the Great’s ancient objective—complete domination of the Baltic.

(b)       The Russians, however, have never yet controlled the Danish Straits in war­time. To do so is certainly one of the prime maritime objectives.

(c)        The Germans demonstrated how to control the Straits—by overland seizure of not only the Straits but also the nearby coasts of Norway and Denmark.

Soviet Objectives and the Danish Straits

What are the Soviet maritime objectives which are dependent on the unrestricted use of the Danish Straits? Before the answer to this question can be speculated on, a more fundamental question must be settled. Do the Soviets want or feel they must control the Straits in wartime? Some experts con­sider that the naval strategy of the Soviet Baltic Fleet has been historically a defensive one, largely a subordinate and supporting role for the ground forces, and that it will continue to be a defensive one. “Russia’s primary objective in case of war would be to close the Baltic exits against penetration by Western task forces and submarines,” wrote Rear Admiral E. Björklund, Royal Swedish Navy recently. The increasing emphasis be­ing given by the Soviets to their Northern Fleet and Arctic bases would seem to corroborate a defensive role for the Baltic and an offensive mission for the Northern Fleet.

This argument, however, neglects two fundamental facts. First, the size of the present Baltic Fleet—approximately six cruis­ers, sixty destroyer types, and as many as 130 submarines—is far greater than that needed for purely defensive purposes. Second, the Russians have repeatedly stated their desire to control the Straits—recall the Molotov statement to Hitler mentioned earlier.[4] The writer concludes that we must assume that the large numbers of submarines in the Baltic have but one destination—North Sea, the Channel ports, and the eastern termini of the Atlantic sea lanes.

We may now return to the first question posed. These are the probable Soviet objec­tives which are dependent on the Danish Straits:

(a)      Offensive:

To sever Atlantic sealanes by losing their Baltic and Arctic Fleets

To attack the United States and NATO Europe by submarine-launched mis­siles

(b)       Defensive:

To secure and dominate the Baltic littoral

To protect and support their armies

To defend herself from Allied naval attack which historically has come through the immovable Baltic sa­lient

Conclusion

For both sides the question is, “How can the Baltic door be kept shut or be opened as desirable?”

In the diabolical weaponry of minewarfare, the Straits can be closed by a vigorous mining campaign—either NATO or Russian. They might also be closed with many sub­surface atomic bursts, an unpleasant and rather permanent solution. Finally, they can be closed or opened depending on which side is in actual possession of the Straits and the adjacent territory.

More important, the Danish Straits will be open or closed to the Communists depend­ing on the resolution and fortitude of the NATO partners. If NATO makes its deter­mination “They shall not pass” plain to the Soviets, the inevitable result will be a gradual reduction in the size of the Soviet Baltic Fleet and a gradual expansion of the Northern Fleet. In the face of a strong determination to keep them closed, the Soviets may decide not to contest the Straits.

In this period of cold war, the Baltic door can be kept open by ship visits. The writer recently participated in a winter cruise aboard USS Northampton into the Baltic, on which the ports of Stockholm and, via air, Helsinki were visited. (USS Barry, flying the flag of Com­mander Destroyer Flotilla 2, visited Stock­holm and Helsinki in the summer of 1960.) It is interesting to note that as soon as Northamp­ton cleared the Straits and entered inter­national waters, inside the Baltic, the ship was under constant escort by a Soviet destroyer-escort. Call signs were exchanged and the proper amenities were made. But the feel­ing was prevalent, as the ship cruised those waters, that the Soviets were attempt­ing to tell us, “Go home—you’re in our pond.”

It would be well to remember that the free world has many friends in the lands that border the Baltic. Some of these friends are officially neutral, although their naval officers are prompt and emphatic in telling you where their real sympathies lie. Others, like the plucky and stouthearted Finns, despite their proximity and the enforced weakness imposed by the Reds, are anxious to have stronger ties with the United States. Still others, under the yoke of satellite status, long for some visible and tangible evidence that this situation is not permanent.

For all these reasons, and for the purpose of continuing knowledge and familiarity of a critical and important area, the U. S. Navy should take an active interest in the Baltic. Whenever operations and conditions permit, we should send ships into the Baltic on friendly visits. Liberty, conditions were never better for U. S. Navy crews.

It should also be remembered that in the Baltic, in those ports where U. S. Navy ships are welcome, only the U. S. Navy can show the American flag. Our planes find it hazardous to fly in that part of the world. Ground troops, of course, cannot march on parade. But the strong and silent ships of our Navy can show themselves proudly in that isolated area and thereby give hope and strength to our friends, and give the lie to what the Soviet Union wants us and the Baltic peoples to believe— that it is their sea. It is not their sea.

Graduated from the U. S. Naval Academy in 1941, Captain Cagle first served in destroyers. Subsequently he commanded fighter squadrons in USS Yorktown and USS Franklin D. Roosevelt. He later served on the staff of the Commander-in-Chief, Naval Forces Eastern Atlantic and Mediterranean as Administrative Aide to the Secretary of the Navy, attended the National War College, and was Executive Officer aboard USS Intrepid. He is presently Commander Striking Fleet, European Representative at SHAPE.

★

TREATMENT SUCCESSFUL—BUT THE PATIENT DIED

Contributed by Captain W. J. Ruhe, USN

During a damage control problem, the Chief Inspector for Operational Readiness aboard a submarine designated one of his party to act as a casualty. The injured man was supposedly bleeding profusely and his breathing had almost stopped. The hospital corpsman had the man carried forward and went speedily to work while the Chief Inspector waited in the Control Room for information on the progress of the patient. Finally, the report came through. The telephone talker fumblingly repeated this message to the Chief Inspector, “The patient is bleeding normally—and his breathing has stopped.”

(The Naval Institute will pay $5.00 for each anecdote accepted for publication in the Proceedings.)