Part Four: The Secret Operations of German Submarines During the Spanish Civil War

The formal outbreak of the Spanish Civil War occurred on July 18, 1936. The day before, rebels stationed in Morocco initiated a military coup, which quickly spread to major cities such as Madrid, Barcelona, and Valencia, but all faced failure. Only in towns in northern Spain did the coup achieve some success. For the rebels, the only hope of altering the balance of power lay in the so-called "African Army" led by Franco, stationed in Morocco. Initially, this army consisted of only 30,000 men, yet it was the most highly trained force in Spain at the time. The autumn offensive launched by this army successfully pushed the front line to the outskirts of Madrid and captured most of southern and northern Spain, ensuring the supply of war materials to the northern regions.

IV. Sink C-3.

3. Regarding Submarine C-3

On December 10, the German Ministry of Defense decided to terminate Operation "Ersula" and ordered the submarines to return the following day. The Italian submarines would subsequently take over the combat patrol mission, and Germany would no longer dispatch submarines to the waters off Spain. Thus, two German submarines began their return along the southwestern coast of Spain after receiving the order

However, in fact, the operational difficulty for German submarines has increased, as the Republican Navy quickly took preventive measures, making it extremely difficult to find attack targets. On December 1, 1936, Captain Grusser of the German Navy submarine U-34 commanded the submarine to launch a torpedo at a Republican Navy destroyer, but the torpedo missed the target and struck the rocks along the shore. Strangely, the Spaniards had no reaction to this peculiar explosion. On December 1, 1936, Captain Grusser of the German Navy submarine U-34 commanded the submarine to launch a torpedo at a Republican Navy destroyer, but the torpedo missed the target and struck the rocks along the shore. Strangely, the Spaniards had no reaction to this peculiar explosion. On December 5, U-34 launched another torpedo at the destroyer "Admiral Servira," but again missed. Shortly thereafter, there was another unsuccessful torpedo attack. The situation for U-33 was not much better; Captain Freiwald faced the problem not of failed torpedo attacks, but of always being unable to occupy a favorable attack position. There were also several instances where the limitations of the mission itself prevented torpedo attacks; once, just as Grusser was about to launch an attack, a British destroyer appeared nearby; another time, on the night of December 5, Grusser witnessed a scene that any submarine captain would dream of: the Republican Navy heavy cruiser "Méndez Núñez" crossing directly in front of U-34 under the cover of a group of destroyers. However, due to the dim light at the time, he was unable to fully confirm the nature of the target as stipulated in the mission, forcing Grusser to abandon the attack. Grusser witnessed a scene that any submarine captain would dream of: the Republican Navy heavy cruiser "Méndez Núñez" crossing directly in front of U-34 under the cover of a group of destroyers. However, due to the dim light at the time, he was unable to fully confirm the nature of the target as stipulated in the mission, forcing Grusser to abandon the attack. All of these situations were promptly reported to the headquarters in Berlin, and these failed combat examples further strengthened the arguments of those who opposed the military operations from the very beginning, with most believing that the likelihood of the mission ultimately succeeding was very low

In 1931, Spain had a total of 12 submarines available, all of which were divided into two fleets: one consisting of "B" class submarines and the other entirely made up of "C" class submarines. Each fleet had 6 submarines, with hull numbers ranging from B-1 to B-6 and C-1 to C-6. Both the "B" class and "C" class submarines were designed by the Dutch, with the latter being an improved version that had a larger displacement. The "C" class submarines were designed by the Dutch Shipbuilding Company, but the construction was carried out by the authorized Spanish Navy shipbuilding company in Cartagena, with the submarines entering service between 1928 and 1930. The "C" class submarines measured 73.3 meters in length, had a submerged displacement of 1,144 tons, and were equipped with 6 torpedo tubes (4 at the bow and 2 at the stern) and a 75 mm deck gun. When operating on the surface with diesel engines, the submarines had a speed of 16.5 knots, while submerged, their speed was 8.5 knots. The maximum operational depth of the submarines was 90 meters, and they had a crew of 40 (including 4 officers). The Spanish Navy was very satisfied with the performance of these submarines; in fact, the "C" class submarines had not experienced any significant malfunctions from the day they were commissioned until the outbreak of the civil war.

In April 1937, the German Navy's pocket battleship "Deutschland" was attacked by the Spanish Republican forces from the air, prompting its sister ship, "Admiral Hipper," to carry out retaliatory shelling against the Spanish port of Almería. This was the only instance of direct public military intervention by the aforementioned countries during the Spanish Civil War. Clearly, this military action demonstrated that the so-called "neutrality" was not genuine, especially considering that Italian submarines and surface vessels had repeatedly engaged in direct combat operations throughout the civil war. Despite the Italian government's persistent denial of this fact, it has long been an undeniable reality. Unbeknownst to many, this also included a small-scale, covert, and even somewhat unsuccessful military operation codenamed "Ersula," featuring the German Navy submarines U-33 and U-34. The entire operation remained classified until after World War II, when a French naval officer, Claude Juan, discovered records of the "Ersula" operation while organizing Nazi Germany's naval archives. The documents revealed that the German Navy's U-34 submarine secretly sank the Spanish Republican submarine C-3 during the operation. Had it not been for the sinking of C-3, this month-long military operation conducted by the German forces at the end of 1936 might have remained unknown to the world.

The German Navy has arranged the operational areas for two submarines as follows: U-33 will patrol the waters between Nauru Point and Paros Point, while U-34 will operate in the waters west of Paros Point. Thus, the Spanish Republican Navy base in Cartagena is directly threatened by U-34, while the port of Alicante is the target of U-33. All submarine personnel are required to swear an oath to keep the operational mission confidential, with safety and secrecy being the primary objectives of the mission, to the extent that even the Spanish rebels are unaware of this operational plan. The submarines will adopt a strategy of submerging during the day and surfacing at night to recharge, maintaining communication with the base through encrypted radio messages. If a submarine is forced to surface during the day and is discovered, it will fly the Royal Navy's white ensign. If forced to withdraw from combat due to mechanical failure or other reasons, the designated port of call must be the Italian naval base located on Sardinia, and all submarine personnel must wear Italian naval uniforms and display the Italian naval flag. According to the operational instructions, the targets of submarine attacks can only be Spanish Republican Navy warships, and targets must be carefully confirmed before an attack, with nighttime attacks to be avoided whenever possible.

On December 11, 1936, at 14:00, the submarine U-34, navigating in the waters off Málaga, began its descent and entered periscope depth. Soon, Captain Grusser spotted the clear outline of a submarine ahead through the periscope; the vessel was traveling at a speed of 11 knots towards a port located 4 miles from the coastal lighthouse in a southwest direction. Perhaps under different circumstances, strict combat orders would have prevented an attack, as the explosion of a torpedo would be clearly visible to those on shore, and there were other vessels in the nearby waters. Soon, Captain Grusser spotted the clear outline of a submarine ahead through the periscope; the vessel was traveling at a speed of 11 knots towards a port located 4 miles from the coastal lighthouse in a southwest direction. Perhaps under different circumstances, strict combat orders would have prevented an attack, as the explosion of a torpedo would be clearly visible to those on shore, and there were other vessels in the nearby waters. More importantly, the entire combat mission had already been canceled. Furthermore, the attack position of U-34 was not very favorable. However, inside the submarine, the crew, having endured long and tedious combat patrols without any results, felt a palpable sense of frustration. Furthermore, the attack position of U-34 was not very favorable. However, inside the submarine, the crew, having endured long and tedious combat patrols without any results, felt a palpable sense of frustration. Now, with the prey in sight, there was no reason not to strike the opponent. After further visual confirmation through the periscope, Captain Grusser was convinced that this was the Spanish Navy's "C" class submarine C-3, and he decided to initiate an attack.

I. The maritime situation at the beginning of the war

At the onset of the war, the Republican forces swiftly dispatched a fleet to the Strait of Gibraltar to implement a blockade, leaving Franco with the option to deploy only two light infantry battalions to Cadiz by sea. Consequently, Franco began to exert every effort to airlift troops to the Iberian Peninsula. Given the limitations in transport capacity, the results of the air drops were commendable. Nevertheless, only infantry and their personal equipment could be airdropped, while heavy equipment had to be transported by sea. Franco withstood pressure and discouragement from various quarters and decided to undertake a bold and risky operation—"either nothing or everything." He organized a small escort fleet to cross the strait. The operation commenced on the night of August 5, and the fleet successfully broke through the blockade and reached its destination. The Republican forces were greatly enraged upon discovering this and dispatched cruisers and destroyers the following day to bombard the rebel base, sinking a rebel gunboat (which was later salvaged and re-entered service in 1937). Aside from this, no other losses were inflicted on the rebels, but the intensity of the blockade was subsequently strengthened, making it increasingly difficult, if not nearly impossible, to break through. However, the situation on the battlefield began to develop favorably for the rebels.

2. The maritime situation in the autumn of 1936

It is commonly believed that Italian submarines were involved in the Spanish Civil War of 1936, and they were the only foreign submarines to have participated in combat operations during this conflict. In contrast, other warships from Britain, France, Italy, and Germany acted as international observers, with the sole purpose of maintaining the neutrality of foreign powers and enforcing the arms embargo