Italy 1917 - Isonzo Battles 10 and 11

The Isonzo Front 1915-1917
(borrowed from the excellent blog 'Things have changed'

Although the Italo-Austrian border snaked for more than 500 miles across the Alps and down to the Adriatic (a distance longer than the Western Front), we have seen in previous posts on Italy (7/7/2015 and 3/11/2016) how the great majority of action occurred along the 60 miles of the River Isonzo front. Only the Austrian gambit from the Trentino region (see Post 3/5/2016) made an incursion into other Italian territory in attempt to cut off the Italian communications to their main front further east. 
The Isonzo front ran from the mountain towns of Plezzo and Bovec in the north down to the Adriatic sea with the river estuary between Montfalcone on the Italian side and the coveted city of Trieste on the Austrian side (see Map). No less than twelve separate battles took place on the Isonzo front from 1915-1917. For the most part they were depressingly 'Groundhog Day' struggles. Following Italian bombardments that grew in intensity with each battle, swathes of infantry would be hurled at Austrian defences that were numerically inferior but strategically placed on mountainous higher ground. Slaughter in these battles was comparable to anything seen on Western and Eastern Fronts. Cadorna, the dominating Italian C-in-C was a good organiser, but his arrogance and pig-headedness resulted in senseless casualties. He sacked hundreds of senior officers for failing to achieve their objectives, or for questioning his tactics. He rarely visited the front, and persisted in his Haig-like belief that one more push would create the breakthrough to open warfare and an advance on Vienna. He treated his troops as fodder, even employing the ancient Roman barbarity of decimation, whereby one in ten troops of a line up post 'failure' were taken out of the line and shot for cowardice in order to stiffen the resolve of the rest. Unbelievable.  
Of the 12 battles, only 6, 11and 12 had strategic impact. The 6th battle resulted in the capture of Gorizia and a toehold on the Carso plain (Post 3/11/2016). The 12th is better known as Caporetto and will be covered separately. Battles 10 and 11 took place in May and August of 1917.

It wasn't as if hostilities ceased and the poor troops got some respite in the winter months. It was that the ferocity of the winter weather - snow, vicious winds, freezing temperatures and avalanches - made mass movements impossible. Men suffered as much (possibly more) as in the major battles, but in localised actions designed to improve defensive positions; create footholds or enhance communications.
In the winter of 1916-17, which saw record snowfalls and dreadful blizzards, both sides made major preparations for the 1917 season of carnage. Boreovic led the Austrian forces in the Isonzo region. Although a Croat rather than Germanic, he was accepted by all as one of Austria's finest generals. Not that that helped his constant appeals for more reserves and equipment. He made the best of his defensive positions lined up, as he was, against greatly superior numbers of Italians. He worked hard to strengthen the new defensive positions he had been forced to take up following the 6th Battle and the loss of Gorizia. Cadorna's larger forces on the front comprised the 2nd Army to the north, led by Capello, and the 3rd Army (south of the Carso plateau to the sea) led by the aristocrat Duke d'Aosta. Capello organised the building of a new road to support the bridgehead east of Gorizia. Cadorna's plan was to blast through beyond this bridgehead, further on to the forbidding Carso plain, drawing the Austrian reserves into that area. Once this was achieved he would launch d'Aosta's 3rd army to take the Monte Hermada heights overlooking the coast and road to Trieste. The town of Kostanjevica was an important target in this move.

Isonzo 10 began on 12th May 1917 with the heaviest bombardment to date, strengthened by British and French artillery. As before, the infantry rush was successful initially. Bridges were constructed across the river, and a broader advance from the Gorizia positions penetrated to the Austrian seond lines 300 metres above the river. In two days Capello's men made incursions into the western end of the Carso and Bainsizza plateaus - physically very different from each other - and both were strategically important. Capello finally took control of Hill 383 (aka Hill of Death to the troops), giving Cadorna a great propaganda prize. So far, so good, despite the predictable counter-attacks from the Austrians that regained some of the lost ground.

Duke d'Aosta - a fine
commander of the 3rd Army

On 23rd May Cadorna ordered phase two, and d'Aosta's 3rd Army swung into action towards Monte Hermada. Supported by over 100 airplanes - an increasing presence in the later battles - they made progress to the foothills and along the coastal marshes but ground to a halt after about two miles. They could not take Kostanjevica.

The 10th battle was judged a success alongside 7, 8 and 9 but all things are relative. The Italian losses for the battle exceeded any other to date. The Austrians also had suffered serious losses, and with their inferior numbers were now stretched very thinly. Boroevic made further appeals to the centre for reinforcements, this time with different and important results. In March 1917, one of the new Emperor Karl's early actions had been to dismiss the vainglorious Austrian Commander in Chief Conrad von Hotzendorf. His replacement was General Arz von Straussenberg, who had considerable experience on the Russian front. He had a constructive relationship with the senior German Military, who had seen Conrad as an irrelevance. Reinforcements that included German equipment were moved from the Russian front and, in early June, strong counter-attacks were launched from the eastern Alpine section of the front, thereby relieving the pressures on Boroevic on the Isonzo. The counter-attacks featured some of the most spectacular and intrepid fighting of the war, involving crack mountain divisions of both sides.
Cadorna's attritional strategy was coming under pressure, not only from these counter-attack on his flank, but from popular and political opinion behind the line. The enormous losses (both sides had lost more than a million men) were sapping the previously strong support for the war. Italy appealed to Britain and France for support in making the 'final' assault across the Carso. Both had major challenges of their own and, despite Lloyd George's enthusiasm to divert from Flanders, could only offer more materiel now, and troops later.
It was, then, with a measure of desperation that Cadorna prepared for what would be his final attempt to lead the breakthrough to the 'road to Vienna'. Whereas Isonzo 10 had focused on two short sections of the front, Isonzo 11 would attack from Plezzo to the sea, seeking for weakness at one of three critical points: Tolmino; Monte San Gabriele, and Monte Herada (see map).
The statutory massive bombardment began on 18th August. By dawn the next day the Italians had secured the river along the whole section and had thrown fourteen bridges across to transport men and equipment. Between Plava and Tolmino two divisions led by General Caviglia scaled the heights of the east bank and made a genuine breakthrough to the Bainsizza plateau. Reinforcements rushed through the gap and in a further three days had taken the ground between Monte Santo and Monte Gabriele. Twenty thousand Austrian prisoners had been taken. Steady but slowing progress was made so that by the twelfth day Cadorna's cavalry was poised to move on to the plateau. But the lengthening supply lines and difficult terrain stymied the cavalry (for the umpteenth time in WW1), and the Austrians held on to sufficient high defensive positions to halt the advance. After a short pause the terrible final phase of Isonzo 11 commenced. Cadorna focused his forces to grind their way along the San Gabriel ridge, a section of about one mile in length, guarding access across the Carso plain and, as a consequence, honeycombed with defensive positions. By 4th September the Italians had taken nearly all of the ridge. Both sides were now desperate. The Austrians rushed in more than thirty battalions to shore up the remaining positions and to launch counter-attacks. The bilateral slaughter continued until mid-September when Cadorna accepted that his famous breakthrough would not be sustained. This phase of the battle had cost over 150,000 casualties, and during 1917 his losses now were approaching three quarters of a million. On the 18th September he informed the Allies that his offensives were at an end.
With heavy irony so typical of WW1 the 11th Battle of the Isonzo reversed the strategy for the two protagonists. Cadorna's armies had been all but smashed on the anvil of mountainous defences, and his own position was precarious. He accepted, at last, the need for defensive positions to hold what he had.

Boreovic - a superb
defensive General

Boroevic, by contrast, now saw that the only chance for his forces (in no better state than the Italians) would be a last chance offensive to force the Italians to retreat. Urgent requests were submitted for German support for such a move.

The French and British leaders failed to appreciate the significance of this shift. Imagining that the Italian front would now go to sleep, they withdrew the reinforcements they had provided reluctantly for battles 10 and 11. In doing so they made their own contributions to one of the Allies biggest defeats in the whole of the war - Caporetto.

Unrestricted submarine warfare 2

The convoy system, belatedly introduced for merchantmen,
averted Britain's looming catastrophe

As recorded in the first part (See Post 16/2/17) the first three months of unrestricted U-boat warfare (UUW) had brought great success to the Germans and induced alarm and crisis activity in Britain. Holzendorff's prescription for the shutting down of Britain's war capability required six months of shipping tonnage at 600,000 tons a month, and the losses for February March and April had averaged more. Perhaps the German optimism was not so fanciful. They had taken the fateful (and ultimately ruinous) decision for UUW in early January. At that point they saw it as the only realistic way for Germany to win outright. They knew about the stretched and exhausted state of their own army, and the low morale and poor physical health of their own population. If they had appreciated fully the parlous state of the Entente powers they might have held off. The French Army was in a worse state than their own; and the Russian effort in the east would shortly cease to exist. The British Empire's resources were keeping the Entente going, but the country itself was on the verge of bankruptcy, and its debts to the USA could not be sustained unless the USA entered the war.  
But now Germany was irrevocably committed to UUW, described by Churchill as ".. one of the most heartshaking episodes of history. It was the greatest conflict ever decided at sea, and almost entirely a duel between Britain and Germany." 

Since their first short period of UUW in 1915, the German strength in U boats had increased greatly. Larger, faster and better armed boats were now capable of making 3-4 weeks patrols. The full complement was now over 150, of which around 70 would be at sea at any one time. Provided the Dover mine barrage could be bypassed (and it could with apparent ease) boats could take the short route from the German and Belgian bases to the vital southern approaches between Ireland and Brittany, and spend 2-3 weeks patrolling in wait for the inbound merchant men. Others took the longer route via the North Sea to patrol the northern approaches round Ireland to the coast of north west England and Scotland.
Once this system was in place, UUW had a rapid and dramatic impact. From a baseline of around 130,000 tons per month in 1916, there had already been a rise late in the year and in January 1917 to more than 250,000 tons sunk. For February the figure was 468,000; for March almost 500,000, and in April it rose to a staggering 869,000 tons. This proved to be the high water mark (sic) for UUW. It still stands as the highest figure ever*. This monthly average actually exceeded Holzendorff's target for strangling Britain in six months, and she was now running out of wheat as well as gold.
Belatedly, the Government and the Admiralty started to get a grip on this dangerous situation. Strenous afforts were made both to improve the protection of merchant shipping and to improve 'seek and destroy' tactics against U-boats. Both were woeful at the start of the year, partly because of the relatively low losses through most of 1916, and the competing pressures for resources to go elsewhere. Arming merchant men to ward off surface attacks from U-boats was the simplest and most obvious measure, but it was a victim of this prioritising - guns were needed everywhere, and only late in 1916 did capacity begin to catch up with demand. In the year 1916 of 600+ merchantmen experiencing surface attack, 76% of those armed escaped, whereas only 22% of those unarmed did so. Q boats (See Post 17/11/2015) were a clever and audacious riposte to surface attacks, although in all of 1915 and 1916 they sunk only 11 U-boats. Perhaps they deterred many more attacks, but by 1917 they were becoming redundant as the Germans were more wary, and were preferring torpedo attacks. Depth charges (still fairly rudimentary) as part of destroyer patrols comprised the other attacking option. There were insufficient destroyers to patrol all of home waters, but at least they were cheaper to build than submarines.
One of Lloyd George's early actions as Prime Minister was to create a new Board of Shipping, merging the offices of Admiralty Chief of Staff and First Sea Lord. Jellicoe was the first holder of this position. The aim was to free up time to focus on improving counter measures. Jellicoe drafted in younger officers to the befuddled Admiralty to deal with this new type of warfare. There were three main areas of focus: better mining; better technology (hydrophones and depth charges); and preparation of convoy plans. The last of these was to be the game changer.
Although convoys had been used for centuries, conventional wisdom held that they were inappropriate for protecting merchant shipping in WW1. This despite the fact that they were in use, successfully, for escorting troopships, and also carrying vital coal supplies across the channel to France**. It was argued that the varying (but slow) speeds and the sheer numbers of merchantmen involved made it too complex an undertaking (wrong). There were insufficient destroyers to protect large numbers of convoys (wrong); and that concentrating ships together would make them an even easier target for U-boats (the reverse proved to be true). Opposition to convoys came from every part of the establishment, the most senior being Jellicoe. Desperation at the position forced a re-think, and production of arguments - mostly from younger officers but also, to his credit, David Beattie, Grand Fleet Commander - to counter the blind logic. Lloyd George and his cabinet were more easily persuade, and prevailed over Jellicoe to insist upon a proper trial. The first experimental convoy left Gibraltar on May 10th 1917, and arrived completely intact. Otherwise overall losses for May remained dangerously high at 600,000 tons. The convoy system was rapidly extended to cover the inbound north and south Atlantic routes. So successful were they over the next three months that the Germans were forced to switch their attacks to un-escorted outbound ships, and gradually these too came under convoy protection (feasible because of the increasing American contributions to destroyer escorts). In October 1917, of 1500 inbound merchant ships only 24 were lost - an astonishing turnaround. Once again the conservative, slow thinking Admiralty had been demonstrably wrong. At Jutland, as Commander of the Grand Fleet, Jellicoe had been prey to this. This time he was the top man at home, but again he shouldered the blame, harshly.

Jellicoe as First Sea Lord.
His disagreement with Lloyd
George cost him his job.

The convoy system all but solved the protection problem and, with increased production from USA involvement, by late 1917 new tonnage far outweighed lost tonnage. The U boat teams were exhausted and many of their best and most audacious leaders had been lost. All possibility of starving Britain to surrender had gone. At the same time the re-invigorated approach to 'seek and destroy' was bearing fruit. Q boats were being replaced by flotillas of submarines that lay in wait for outbound groups of U-boats in the north sea and the channel. The effectiveness of mining tactics improved throughout 1917, particularly in the Channel with the appointment of the dashing Admiral Roger Keys to command of the Dover patrol (see Post 13/9/2015). The previous Dover barrage of 1916 had been ineffective in blocking the Belgian based U-boats from using the Channel route. In the November 1917 reshuffle when Wemyss replaced Jellicoe as First Sea Lord, Keyes replaced Admiral Bacon in the important Dover defensive role. Keyes immediately doubled patrols along the barrier, now laid with the new deep, horned mines, and organised night time illuminations to drive the U boats deeper toward them. This prompted great activity in the Channel, and ultimately closed it off as a route for U-boats.
By early1918, with improving depth charges and listening technology, the U-boats were becoming the hunted rather than the hunters. Britain had ridden out the blockade crisis and the risk of a precipitate defeat.

 * Even Hitler's modern U boat fleets in 1942 at their peak could not match it. 
** France's own coal fields being under German occupation