The Battle of the Atlantic was the longest continuous running battle of the Second World War. Between 1939 and 1945, the Axis powers dispatched hundreds of submarines to the cold dark waters of the Atlantic in an attempt to strangle the flow of supplies and materials being sent to those countries still opposing the massive Axis onslaught that initiated the war. The main recipient of these desperately needed supplies was Britain; at first as a means to keep them in the war, latter to build up military strength for a cross channel invasion. If this attempted blockade by the Axis was successful, and England was forced to capitulate in the early stages of the war, chances for an ultimate Allied victory would have been greatly hampered if not outright eliminated. The German Navy (Kriegsmarine), was by far the dominate participant in this critical fight for the Axis. They would send into battle some of the most advanced submarines of the time, guided by many of the greatest commanders in the history of underwater warfare. And while the Mediterranean was the main area of battle for the Italian Royal Navy (Regia Marina), it too would send her submariner warriors to the Atlantic to assist in the Axis cause. During the three years of Italian participation in this epic struggle, Italy’s submarine crews fought with heart and valor during their war patrols on and below the waves of this immense battlefield. At the forefront of the Regia Marina’s submarine effort was the Leonardo da Vinci, the most lethal Italian hunter of Allied shipping throughout the entire Second World War.
The Leonardo da Vinci submarine was a Marconi-class submarine, and was first launched September 16th, 1939. She was 76.5m long, and displaced 1465 tons fully loaded. She could reach a top speed of 17.8 knots on the surface, and 8.2 while submerged. The da Vinci was armed with 1 x 100 mm deck gun, 4 x 13.2 mm anti-aircraft guns, and 8 x 21″ torpedo tubes. On September 22nd of 1940, she departed from Naples for Bordeaux in occupied France, home of Italy’s main Atlantic submarine base known as BETASOM. Given Command of the da Vinci to usher her into this phase of the war was Ferdinando Calda. Navigating safely across her “home waters” of the Mediterranean, the da Vinci passed undetected by the British at the critical juncture at the Straight of Gibraltar on the 27th, and headed off into the wide expanse of the Atlantic, where she immediately began operations. Harassed by two British destroyers during an early engagement she undertook on September 30th, a quick crash dive led to her escape from potential destruction. The Leonardo da Vinci reached the safety of Bordeaux on October 31st, her first appearance at her new home port. During her maiden patrol, she had come up empty on a few attempted intercepts with Allied vessels; much more success for the da Vinci lay ahead however.
As stated, success would come for the da Vinci and her crew, but it would not come quickly. She embarked on two more unsuccessful war patrols in succession to begin her time in the Atlantic; one lasted December through January, and the other spanned March through April of 1941. Both were carried out in the waters off of the coast of Ireland. She returned to Bordeaux from the cold north after each voyage without a kill, although valuable lessons and experience had been gained by her crew.
The technical and performance limitations of Italian submarines operating in the northern Atlantic waters were becoming quite obvious by the spring of 41. Italian submarines were for the most part larger than their German counterparts, making them easier to detect and or fall under attack by the Allies. Italian doctrine on submarine warfare had generally called for their subs to operate beneath the surface while engaging a vessel. The initial torpedo attack would come while submerged, and then the sub could rise to the surface to finish off the target if applicable. Longer periscopes were essential to fit this type of submerged warfare, thus a larger conning tower was required on Italian submarines in comparison to the German U-Boats. In contrast, German submarines would mostly engage their targets while on the surface, hence their subs were designed to give as little of a silhouette as possible. This accounted for some of the greater profile and larger size Italian subs had when viewed against their Axis partner, but finer overall engineering and design by the Germans must be recognized when directly comparing the two fleets. Italian subs also took longer to complete an emergency dive, which of course being able to conduct a quick escape is a very valuable asset when attempting to avoid a surface attack or engagement. Again, the submarines of the Regia Marina were built to match Italian doctrine of attacking below the waves, not necessarily designed to make a quick retreat after an initial engagement. This led to less emphasis or focuses on that ability in the design and production of Italian submarines by their engineers, and in turn was a key component in the construction of German subs. Also, an additional shortcoming for the Regia Marina was the fact that their submarines could not match the speed, submerged or while on the surface, of the German U Boats.
The preferred method of attack for the Germans was to deploy their subs into “Wolf Packs”; several submarines working in unison to track and attack a ship or convoy. The submarines of the Italian navy had difficulty working with the Germans in this type of joint operation, mainly due to communication and coordination problems with their German counterparts. The Kriegsmarine leadership also felt that Italian submarine officers were lacking in quality when compared to their own. The much colder waters of the North Atlantic also began to take its toll on the Italian submarine fleet, which had been envisioned and designed to operate mainly in the warmer Mediterranean waters.
Thus starting in the spring of 1941, taking all of these factors into account, Italian submarines would be mainly deployed in the central and southern waters of the Atlantic. Regia Marina doctrine would also once more generally call for their submarines to operate independently, instead of using the German “Wolf Pack” tactics that were proving inefficient for the Italians. So as the Leonardo da Vinci prepared for her next patrol, she would do so not as a member of a pack, but as a lone predator stalking her prey.