On the Edge of the Great War: Italian Combined Operations in the Adriatic, 1915-18

While a recent spate of books and model kits has sparked a surge of interest in Austro-Hungarian military aviation, little has, as yet, been written about the Dual Monarchy's principle western adversary, Italy, and even less about how air operations fit into the overall conduct of the war in the Adriatic. Yet, the Italian front produced many of the lasting military innovations that emerged from the Great War. The tactics that produced the great breakthroughs on the Western Front in 1918 and combined operations—the close coordination of the air, naval, and ground forces that would characterize all future wars—were first perfected here. This brief sketch touches on the main features of this interesting period in military history.

Italian War Aims and the Historical Background of the War in the Adriatic

Italy entered World War 1 a year late (in May 1915) and on the wrong side (by pre-war calculations). The resulting ill-preparedness of its forces and the peculiar geographical circumstances of the battle front thus forced Italy to a series of improvisations that are of considerable interest to the historian and modeler. Italy’s policy in the last half of the nineteenth and the first half of the twentieth centuries was driven by an unfinished nationalist agenda dating back to the foundation of the modern Italian state in 1870.

Prior to 1870, northern Italy, from Milan to Venice, was ruled by Austria, one of the super-powers of the period. The Pope held a broad strip of central Italy composed of the provinces of Tuscany, Umbria, and Latium, while the south was in the hands of the moribund Franco-Spanish Bourbon dynasty. By skillful military and diplomatic exploitation of the turmoil created by the Italian Risorgiamento (“Resurgence” or national uprising), the Duke of Savoy, Victor Emmanuel II, turned a small but prosperous hereditary domain between Turin and the French and Swiss borders into a national state. He first arranged his accession to the thrones of Naples and Sicily and thus gained control of the entire area south of Rome. At first, he tried to avoid direct conflict with Austria. But popular agitation in the north and savage repression by Austria’s army and secret police soon forced Victor Emmanuel to confront Austria militarily. With the help of France and Napoleon III, he managed to defeat the Austrian army at Solferino in 1859. Austria agreed to a brokered peace, and, for a time, the focus of Italy’s struggle shifted south to the heart of Italy, Rome and the Papal states. But once the Papal forces had been routed and the nation unified, Italian nationalism began to take a second look at the peace won at Solferino.

The peace had left Austria in control of many regions that were or had been Italian by language, culture, history, or tradition. The Habsburg empire still held the mountainous, Dolomite region around Bolzano and Trent that Italians called the province of Alto-Adige, as well as Venice, the industrial city of Trieste, the port city of Pola, and the old Venetian colonies of Istria and Dalmatia in present-day Croatia and of Albania. Like present-day Serbian nationalists, Italian irredentists demanded a greater Italy uniting these far-flung and disparate territories with the motherland. In 1866, Italy joined Prussia in the Austro-Prussian War and won Venice at the subsequent peace talks. But there things stood until 1914.

In 1882, a colonial dispute with France in North Africa and, perhaps, the hope that German diplomacy might help Italy regain its Austrian territories, led Italy into a somewhat surprising alliance with Germany and Austria-Hungary. The treaty of the Triple Alliance required that each signatory nation support defensive wars forced upon the others by outside aggressors. When World War 1 broke out, both Germany and Austria pressed Italy to honor its treaty commitments, which had been renewed as recently as 1913. But Italy remained aloof on the grounds that the war was not defensive (since Austria had invaded Serbia). In actuality, the government probably wanted to see which way things were going before it entered the fight. But, by 1915, British diplomacy, irredentist agitation (led by the charismatic proto-fascist poet Gabriele D'Annunzio), and Italian popular sentiment caused the government to renounce the Triple Alliance and declare war on Austria. Italian policy did not at first envision war with Germany, and war was not in fact declared until 1916. Italy simply hoped to realize its eastern territorial ambitions by rapidly moving against an Austrian Empire weakened by war with Russia.

The Realities of Italy's Military Situation in 1915

Italy's optimistic, pre-war goal was not, of course, achieved. Austrian forces were not easily defeated by Italy’s numerically superior but inexperienced forces. The terrain favored the defense. The Italian army had to advance along a narrow, coastal front bounded by the deep valleys and vertiginous precipices of the Dolomitic Alps on the left and the shallow, marshy waters of the Venetian lagoon on the right. It had to engage dug-in Austrian forces head-on, in the knowledge that failure might prove disastrous: the enemy was perilously close to major Italian population centers at Verona, Vicenza, and, above all, Venice. The long, populous coastline of the Italian Peninsula was equally open to attack by Austrian units operating from the fortified harbors at Pola in Istria and Durazzo in Albania. But Austria’s Dalmatian, Serbian, and Albanian coastlines were not equally vulnerable. They lacked the sheltered, developed port facilities and good east-west, inland communications that invaders required, and chains of fortified islands screened coastal shipping and population centers from the powerful Italian Navy. The qualitative and numerical superiority of the Italian battle fleet was largely neutralized by the need to avoid engagements in confined coastal waters, where Austria might achieve a local advantage, and by the need to guard against sorties by the Central Powers. Austria had a small but nonetheless powerful navy that might have caused major problems if it attacked the Otranto Barrage, the vast blockade, mine and net barrier that closed the southern extremity of the Adriatic to Austria. The powerful German battle-cruiser Goeben and the cruiser Breslau were lying in wait in Turkish waters, looking for any relaxation of vigilance among the Allies (powerful Russian, British, French, and Japanese task forces concentrated in the eastern Mediterranean for much of the war solely because of the Goeben). Large, modern Italian dreadnoughts simply could not be risked in anything less than a general engagement on the high seas.

Tactical and Technical Innovations

Under these conditions, Italy was forced to seek innovative technical and tactical solutions to the military and naval problems confronting it. In general, she pursued a conventional aim—opening and turning one of the enemy’s flanks—by unconventional means.

On its Alpine flank, the Italian army tried to adapt traditional military skills and roles for mountain conditions. The north-south ranges of the Dolomites were treated as the objects of a classical siege carried out on a vast scale. Troops were moved and supplied by a system of funicular railroads and cableways. Mountains were hollowed out into vast fortress complexes. New techniques for firing and spotting artillery were developed. Specialized elite units proliferated: Alpini for climbing sheer rock faces and Arditi—the first storm troops—for infiltrating defense lines, clearing wire, and assaulting strong points. These units received special equipment, including body armor, special armored shields, extra grenades, and the first submachine guns to be issued on a large scale—the twin-barrel, 9-mm Villar-Perosas. (Right) The Villar-Perosa submachinegun.

Over the front, the mountains and the sea dictated the nature of the air war. The constricted nature of the battle front made the classical two-seat tactical reconaissance airplanes unusually vulnerable to fighter attack. Enemy fighters could concentrate on a narrow slice of airspace even though there were never all that many fighters available to the Austrians. At the same time, the high altitude performance, long range, and agility demanded by mountain flying were often too much for the heavily loaded two-seaters. Accordingly, Italy pioneered the use of high-performance, single-seat photo-reconnaissance planes derived from fighters. The Ansaldo SVA made many notable long-range flights in this capacity, culminating in D'Annunzio's famous, formation leaflet raid over Vienna with the 87° Squadriglia "La Serinissima." The mountains also encouraged the development of strategic bombers and bombing doctrine. The Alps shielded the Austrian heartland and its capital from any reasonable chance of capture by Italian ground forces. Only the air weapon could threaten the enemy's centers of power and offer hope (however desperate) of an early termination of hostilities. Yet the single-engined two-seater was even less suited to this role. Single-seat SVA bombers did carry out raids with some succes, but they could carry no more than a few light bombs for a short distance (bombs could not be carried on the Vienna raid, hence the leaflets). The Italian military thus took an early interest in the heavy bombers that were offered by the Caproni firm. These could reach distant targets with more bombs than a two-seater could carry to the front lines. Alternatively, they could carry huge bombloads over the battlefield, supplementing the weak Italian artillery during the hours of darkness. Capronis also proved themselves invaluable for supporting the special operations that proliferated on the Italian front. Such missions generally involved the dropping of agents or nationalist agitators along with arms, radios, or carrier pigeons. The celebrated Maj. William Barker carried out one of these operations.

On the Adriatic side of the battlefield, specialized aircraft and a plethora of small craft took over the duties of the absent capital ships. Shallow-draught monitors and armored batteries provided heavy-gun fire support for the infantry from waters too shallow, too constricted, and too dangerous for battleships. Barges and special armored landing craft gave the infantry and their artillery limited, tactical mobility. Most of all, fast, flat-bottomed motor torpedo boats and gunboats did the main work of the battleships and destroyers, deterring the small but nonetheless powerful Austro-Hungarian battle squadron from all but one, disastrous sortie. All the while, the small boats were tireless in raiding enemy anchorages, escorting coastal convoys, and supporting infantry with naval gunfire.

MAS

The MAS was derived from an unsuccessful, prewar SVAN (Societa Veneziana Automobili Navali) design for a torpedo-armed motor gunboat. SVAN specialized in large, fast power boats, so the MAS closely resembled the off-shore racing craft of the day. The crew huddled in an open, midship cockpit or clustered near the stern enjoying what little protection the long, rounded turtle-back deck had to offer. Because they had to be cheap, MAS were built of plywood using the most easily built hull form, a long, slender hard-chine hull with a knife-edge stem and a flat, planing bottom aft. Sea-keeping was, as a result, poor in all but the smoothest water. If any sort of speed were maintained in a seaway, pounding quickly made life unbearable for the crew. But given adequate engines—typically a pair of 225-hp Isotta-Fraschini L.56—and calm conditions, the resulting boats could easily outrun even the fastest destroyers.

This happy coincidence led to the first change of role for the MAS. The powerful engines were not happy or economical at the low rpm dictated by patrol work and the poor seakeeping qualities of the hull. The small depth charges that MAS could carry were of little value as anti-submarine weapons, and the noise of their hulls and engines made their primitive hydrophones useless for detecting submerged targets. So, when the first boats were delivered, the Regia Marina was at a loss as to how it might use them. The navy flirted briefly with the idea of using its powerful little MAS as small, fast minelayers. But the availability of the 45-cm Whitehead-Napoli torpedo made the silurante (motor torpedo boat) role unexpectedly attractive. These torpedoes were being retired as quickly as possible because their warheads were deemed inadequate for use aboard contemporary destroyers. The success of a simple, side-dropping gear like that used on late-model, Second World-War PT boats meant that no expensive launch gear would be required, and crews could be recruited from among the motorboat enthusiasts of the voluntary naval reserve.

Offensive use of such small vessels nonetheless presented problems. MAS were, of course, vulnerable to air attack, operating, as they did, close to shore in a narrow sea. One to four 6.5-mm Colt “potato-digger” machineguns provided some nominal anti-aircraft defence, but the boats were largely defenseless in daylight. They had to work closely with friendly aircraft. Given clear visibility, they could also be hit by the gunfire of shore fortifications, the secondary batteries of capital ships, and pursuing destroyers. A hit from even a small shell would generally destroy the boat. So MAS had to have the support of friendly destroyers that could screen their retreat. To get themselves to the Italian destroyers' patrol line, the MAS crews pioneered the near-universal MTB tactic of using shallow-fused depth charges and smoke floats to discourage pursuit. These tactics were so successful that only one MAS was lost to enemy action during the war. Accidental gasoline fires and collisions proved to be the principle threat to the boats.

Given their limitations, the siluranti had to carry out most of their missions at night, much like their WW-2 descendents. They would lie in wait off anchorages or among the rocky islands and net defenses that kept Allied destroyers and submarines away from Austria's Dalmation convoys. Using their anti-submarine hydrophones to listen for propellers and their silent-running, 5-hp, Rognini electric motors for station-keeping, they would wait until a convoy or patrol vessel attempted to enter the harbor. Then, still on electrics only, they would tuck in behind, slip through the boom defenses, launch their twin 45-cm torpedoes, and retire at high speed in the resulting confusion. These operations were so successful that the Austrians mounted an unsuccessful commando raid on Ancona with the express purpose of seizing MAS for their own navy.

Smoke and depth charges were a useful defensive expedient, but they did nothing to answer the other shortcoming of an all-torpedo armament: the expense and uncertainty of attacking the shallow-draft coastal shipping and sailing vessels Austria relied on for much of its transport with expensive and temperamental high-technology weapons. Italian boats were, moreover, increasingly subject to attack by Austrian small craft. While Austria never managed to produce its own equivalent to the MAS, it nonetheless possessed a small force of armed launches, motor gunboats, picket boats, and impressed motor yachts that could, at times, engage MAS. Gun-armed MAS would thus be invaluable in inshore waters where friendly destroyers could not safely follow. Many were accordingly outfitted as cannoniere with a quickfiring, 47-mm cannon mounted on top of the forward hatch. Maids of all work, cannoniere screened siluranti, destroyers, and torpedo boats (small destroyers), escorted inshore convoys, recovered downed airmen, landed spies and saboteurs, covered the flanks of coastal advances, and functioned as miniature navies on the large, glacial lakes that grace the foothills the Austro-Italian border region.

But it is the siluranti that are most often remembered, largely for two epic victories carried out under the leadership of one man, Capt. Rizzo. On the night of 9/10 December 1917, Rizzo set out with two boats, MAS 9 and 13, to cut off the Austrian battleships Wien (launched 1895, 5600 tons, four 24-cm and six 15-cm guns) and Budapest, then engaged in their nightly bombardment of Italian shore batteries. To save time, fuel, and wear and tear on the boats’ highly tuned gasoline engines, destroyers towed the MAS to a point near the Austrian naval base at Trieste. The battleships had beaten them back, so Rizzo decided to enter the harbor itself. Using hydraulic shears brought for the purpose, the Italians cut the three 60-mm steel booms that guarded the mouth of Muggia bay and slipped into the harbor on electric power. At 200 meters, the boats salvoed their torpedoes against the two pre-dreadnoughts. At 02:32 MAS 9’s weapons hit the Wien amidships and sank her almost immediately. MAS 13 missed her target. Both boats then slipped away unobserved. On 10 June 1918, Rizzo and the MAS fought a still more spectacular action against an Austrian battle fleet in daylight. Fearful of mutiny, Bolshevism, and revolution (all of which in fact broke out within a matter of weeks), the Austrian navy decided to boost morale with a sortie against the drifters and destroyers tending the Otranto barrage. A fast, unexpected sally might well destroy the blockade before Italian heavy units could react, allowing German and Austrian U-boats free access to the Mediterranean for the first time in years. Two dreadnoughts, the sister ships Tegethoff and Szent Istvan (launched 1914, 21,370 tons, twelve 30.5-cm and twelve 15-cm guns) set out with a strong escort of destroyers. Alerted by Italian reconnaissance, Rizzo in MAS 15 led MAS 21 and an escort of torpedo boats to intercept the raiders. The dead calm and haze let the MAS close the Austrian battleships unseen and at high speed. At the last minute, Tegethoff managed to evade the torpedoes launched by MAS 21. But Rizzo’s torpedoes hit the brand-new Szent Istvan amidships. She immediately started to list and, in minutes, rolled over and sank with all hands. Again favored by near perfect conditions, the MAS easily out-ran pursuing destroyers despite having to weave through heavy and accurate shell fire. What was to have been a morale builder thus proved to be an absolute disaster. The Austrian ships fled back to their bases where mutineers—sailors’ Soviets and Yugoslavian nationalists—seized them shortly after.

In the aftermath of Rizzo's attack on Wien, the Austrians strengthened their boom defenses until hand-held hydraulic shears could no longer overcome them. The Italians responded with a special type of MAS, the Grillo or "Cricket." This was a slow, quiet, electrically driven boat inspired by the British rhomboid tanks. It combined the flat-bottomed hull of a landing craft with a pair of 45-cm torpedoes in side-dropping gear and two hook-studded, engine-driven chains mounted on either side of the hull. The Grillo could approach boom defenses quietly and clamber over them, much like a tank crushing barbed wire. Once inside the anchorage, it would attack with its torpedoes and retire the way it came. The Grillo was not very successful in action. The chain mechanism produced a frightful clatter that all but negated the advantage of the silent, 15-hp electric motor. They were usually destroyed by shellfire before they got over the booms. Nevertheless, the Austrian navy was interested enough to raise and copy a sunken example.

Monitors

If the MAS held the limelight and established a tradition in the Italian service, the less heralded monitors and mobile batteries performed no less valuable a service with rather less glamor. While the MAS were sleek and fast like rich boys’ yachts, resplendent in their dove grey hulls, cream turtlebacks, and clear varnished mahogany brightwork, the monitors were grubby, ill-handling things built on scow and pontoon lines, all ugly as sin.

The Italian vessels were especially awful looking. The first ones were in fact Venetian garbage scows with single field guns in the cargo wells and light armor hung over the gunwales. Purpose-built barges later carried batteries of army field artillery and infantry firing through loopholes in the sides. The final expression of this school of design was the monstrous, self-propelled, floating battery Faa’ di Bruno. This was not really a boat at all. The hull was a rectangular steel box with a crude, triangular prow welded on. For most of its length, the deck formed a shallow, armored pent roof over the hull. The main armament, a pair of 38-cm (15-in) 40-cal naval guns, sat in a bizarre, open-topped turret amidships surmounted by a huge, armored umbrella. This, together with four 14-pdr AA guns, two 1.5-pdr pom-poms, and a bunch of Colt machineguns, was carried on a mere 2854 tons (i.e., roughly a Fletcher- class destroyer of WW2). The thing drew only six feet—surely a record! Needless to say, her mere 465 hp on one screw had its work cut out for it just managing the thing’s nominal maximum, 4 mph (about the speed of a light breeze or a brisk walk).

Britain had pioneered the use of monitor-type vessels on the coasts of Flanders and Gallipoli, where they made good use of otherwise obsolete and odd-caliber heavy guns that were no longer of use to the first-rate ships. In keeping with her maritime traditions and naval bureaucracy, England’s efforts were rather more seamanlike than the Faa’. Performance was generally below expectations, but several managed to sail to distant waters under their own power. Most played no role in the Adriatic, which was viewed by the Admiralty as too dangerous even for these expendable, inshore bombardment vessels. An exception was made, however, for several vessels of the 12-in class, the smallest -gunned of Britain’s large monitors. These had Edwardian 35-cal gun used on the pre-dreadnoughts of the 1880s. This weapon no longer had a chance against modern warships, but it offered a higher elevation than most of its larger, more modern, flatter-trajectory competitors. Two 12-pdr anti-torpedo boat guns, one 3-pdr A.A. gun, one 2-pdr A.A. pom-pom, four 0.45-cal Naval Pattern Maxim machineguns gave the vessels some limited protection against air and surface threats. Huge anti-torpedo bulges protected the hull from mines and underwater attack. Salvaged, reciprocating steam machinery gave 2310 hp on two shafts, each with a 7.5-ft screw. Because of the hull shape, this translated into a mere 8 knots maximum speed—adequate, but barely so. The 12-inch monitors were 80 ft long with a 20-ft beam and a draft of 10 ft. They displaced 5599 tons.

The Earl of Peterborough, shown in the accompanying illustration, was one of the vessels that served in the Adriatic. The Edwardian turret machinery was complex and fragile, particularly after the elevation of the guns was increased to get better range. Since air attack was out of the question when they were built, the thin top plates of the turrets were proof against splinters only. Austrian naval aviation was both aggressive and competent, so Peterborough’s turret roof and the rear of its turret ring were given extra protection in the form of a layer of sand bags. I have shown the tripod mast camouflaged with the geometric shapes that most 12-in monitors carried in the hope of baffling enemy range finders, though my photo of this particular ship did not show the mast area.

Given the flat, featureless coast, the monitors operated much like land-based artillery. Unlike more orthodox naval vessels, they served almost entirely in the indirect-fire role, adjusting their aim against buoys in response to the reports of forward artillery observers ashore or in the air.

Naval Aviation

In support of these varied surface craft, Italy developed an extraordinary range of water-based, high-performance fighters, bombers, and reconnaissance airplanes. Along the Adriatic, Austria-Hungary and Italy faced each other across 75-100 miles of water along a front stretching 400-500 miles. Aircraft could attack almost any point along the enemy coast, provided that airbases could be found close to the water. This was frequently a problem for landplanes, however, particularly in Italy. To the south of Venice, the malarial swamps, mudflats, dunes, and drainage canals of the Maremma provided few suitable fields reasonably close to the coast. Much of the land further west was, in any case, rice paddy, subject to periodic inundations by the Po and its tributaries. This same area was, however, amply supplied with small anchorages, sheltered canals, and fishing ports that could support marine aircraft.

Italian industrial capacity was still modest when war commenced. Italy could not supply sufficient numbers of indigenous warplanes. So Italy relied heavily on imported and license-built foreign types. Obtaining adequate numbers of coastal patrol and convoy escort aircraft posed a particular problem given Italy's long coastline. Accordingly, the Regia Marina imported large numbers of French FBA flying boats. These were somewhat small for use in the North Sea and the Bay of Biscay, so they were not used extensively by the French and British, who preferred longer legged Curtiss, Felixstowe, and Tellier boats. Over the short ranges typical of the Adriatic, FBAs were entirely satisfactory, however. FBAs were used extensively for antisubmarine patrol, convoy escort, and general, maritime reconnaissance.

The first successful indigenous type, the Macchi Type L general-purpose flying boat, was a direct copy of a captured Lohner Type L, made at the express request of the Italian authorities. Some batches of the aircraft introduced a semi-enclosed cabin for the crew or a different, rounded fin and rudder, but all were essentially similar to their Austrian originals. An Isotta-Fraschini V4B (shown below) substituted for the Austro-Daimler of the captured machine. Bombs, depth charges, and 6.5-mm Revelli machineguns were the usual armament. But many carried a 25-mm, quick-firing Revelli cannon instead, often supplemented by a twin-barreled, 9-mm Vilar-Perosa submachinegun.

By combining its experience reverse engineering the Lohner with that gained from license manufacturer of Nieuport scouts, Macchi went on to produce the most successful flying boat fighter of all time, the Macchi M.5. This combined the L’s Lohner-like hull and V4B engine (V6B in late-production machines) with the graceful sesquiplane wings of a Nieuport 17. The resulting boat was fast (117 mph) and maneuverable enough to fight landplanes on almost equal terms. Early models were armed with the unreliable, 6.5-mm FIAT-Revelli machine gun, but later aircraft substituted a pair of Vickers guns. In 1918, M.5s were starting to be replaced by the Macchi M.7, which standardized on the more powerful V6B engine and introduced a new wing cellule.

The Otranto Barrage

The MAS, the strong air patrols, and even the monitors were all deployed in support of one of the more extraordinary naval undertakings of any conflict: the Otranto barrage. From the Allied point of view, Italy’s entry into the war meant one thing, the end of easy U-boat campaigns in the Mediterranean. Britain depended on reliable communications with its Empire via the Suez Canal (especially India and Australia) for supplies of raw materials, food, and troops. France was also dependent up to a point on its African colonies, which supplied key naval bases as well as Berber and Senegalese legionaires. When war broke out, Austria was circumspect about allowing German U-boats safe haven in its harbors. But they were allowed in and out at least at times, and the Dual Monarchy’s own small U-boat force was a concern. Italy’s declaration of war let the Allies try something unprecedented: a net barrier across the mouth of the Adriatic, between Otranto in Italy and Albania, defended by mines and armed trawlers and supported by a belt of hydrophone stations (a precursor of the US COSUS system). None of it was very effective—the sea was just too big and the netlayers too few. But, as we have seen, the Barrage seriously hampered the Austrian Navy’s movements and led to its one great defeat at sea, the loss of the dreadnought Szent Istvan.

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© 1996 by Robert Craig Johnson. Part of a series first published in Eagle Droppings, the Newsletter of the Rocky Mountain Chapter, IPMS/USA.