Operation Plonk

'Plank' was the Allied offensive to break through the 'Paula-Linie' (i) defences in north central Italy, leading to the capture of Florence (17 July/5 August 1944).

As Lieutenant General Mark W. Clark’s US 5th Army and Lieutenant General Sir Oliver Leese’s British 8th Army moved to the north along the 'leg' of the Italian peninsula after the fall of Rome on 4 June 1944, the capture of Livorno on the west coast, Arezzo in the centre of the country and Ancona on the east coast meant that the Allies could now focus their attention on the seizure of Florence on the Arno river.

The campaign which followed pitted Lieutenant General S. C. Kirkman’s British XIII Corps against General Alfred Schlemm’s I Fallschirmkorps and the right wing of General Traugott Herr’s LXXVI Panzerkorps of General Joachim Lemelsen’s 14th Army. Since the fall of Arezzo, the XIII Corps' front had been increased to include the sector of Général de Corps d’Armée Alphonse Juin’s Corps Expéditionnaire Français (French Expeditionary Corps), in which Major General D. Russell’s Indian 8th Division had been committed to combat once again after a very short rest and refit. The plan developed by Kirkman was to develop two strong armoured thrusts toward Florence, using his two armoured divisions with Major General A. D. Ward’s 4th Division acting as a link between them. Major General V. Evelegh’s 6th Armoured Division was to advance along the east bank of the central reaches of the Arno river, which was far from good terrain for the deployment of armour: there were only about 4 miles (6.4 km) between the river, which was to form the division’s left boundary with the 4th Division, and the Pratomagno massif which dominated the whole valley. Major General W. H. E. Poole’s South African 6th Armoured Division was to advance from Radda to Greve on the western side of the densely wooded Chianti mountains extending to the north-west through Monte Maione (Pt 812) toward Florence. The 4th Division was to clear the area between the eastern side of the Chianti mountains to the central reaches of the Arno river, and the Indian 8th Division was to cover the XIII Corps' left flank.

Should the Germans resist strongly, Kirkman intended to bolster his thrust by bringing up from reserve Lieutenant General Sir Bernard Freyberg’s New Zealand 2nd Division to help the British 6th Armoured Division.

The 14th Army fought its part of the battle on a series of map lines which led back to the position to the south of Florence which, the I Fallschirmkorps was informed on 20 July, must be held for some time. This was the 'Paula-Linie' (i) running from Montelupo at the junction of the Pesa and Arno rivers in the area some 4 miles (6.4 km) to the east of Empoli, across to Monte Scalari (Pt 787) and on to Figline on the central reaches of the Arno river. With Generalleutnant Walter Fries’s 29th Panzergrenadierdivision, Generalleutnant Heinrich Trettner’s 4th Fallschirmjägerdivision and Generalleutnant Karl Faulenbach’s 356th Division under his command, Schlemm was on 17 July about to take up an intermediate line covering Castelfiorentino, Tavernelle and the western ridges of the Chianti mountains, and on this day Monte Maione (Pt 812) was fixed as the junction between the I Fallschirmkorps and LXXVI Panzerkorps of Generaloberst Heinrich-Gottfried von Vietinghoff-Scheel’s 10th Army, which was holding a line from a point to the south of Montevarchi along the Arno river to the north of Arezzo to the Alpe di Potito.

The British 6th Armoured Division, with Brigadier F. N. Mitchell’s 26th Armoured Brigade in the van, began its thrust to the north-west from Arezzo on 17 July with Castiglion Fibocchi as its objective. The 4th Division advanced to the north across the hills towards Montevarchi, which it neared on the following day. Both divisions had now come up against the LXXVI Panzerkorps' strongly held 'Irmgard-Linie' position. Failing to gain Castiglion Fibocchi, the British 6th Armoured Division sent some tanks across the central reaches of the Arno river at Laterina, but also failed to make progress on the western bank. The 4th Division was stopped by Generalmajor Hanns von Rohr’s 715th Division, newly arrived and holding the high ground to the north-west of Montevarchi.

By this time the British 6th Armoured Division’s fears about the unsuitability of the terrain for armoured operations were being fully confirmed.

The South African 6th Armoured Division fared rather better. This formation had advanced on a two-brigade front during 16 July on the axis of the road linking Castel di Brolio and Radda, Brigadier R. J. Palmer’s 12th Motor Brigade astride the road and Brigadier A. F. L. Clive’s 24th Guards Brigade protecting its right flank along the western slopes of the Chianti mountains. The 24th Guards Brigade made good progress on 17 July and entered Radda on that night, when the I Fallschirmkorps pulled back to the north in order to maintain its alignment with General Fridolin Ritter und Edler von Senger und Etterlin’s XIV Panzerkorps, which had been forced to withdraw under pressure from the 5th Army. The advance of the South African 6th Armoured Division was then directed to securing the main features in the Chianti range, namely Monte Maione (Pt 812) and Monte San Michele (Pt 892), each of these more than 2,000 ft (610 m) high. The 24th Guards Brigade took the former by surprise after a fast night march on 18/19 July and then pushed on farther, with the support of the tanks of the Pretoria Regiment, over the forested hills to take Monte San Michele on 20 July. The 12th Motor Brigade advanced over equally rough country on the left to Monte Querciabella (Pt 845). The South African 6th Armoured Division had captured the highest points in the Chianti mountains, and from these the terrain fell steadily down to the Arno river valley and Florence.

The 715th Division's loss of these peaks compelled the LXXVI Panzerkorps to withdraw to its next delaying position, which lay in front of San Giovanni. Kirkman appreciated that there was still to be some hard fighting before his formation reached the lower reaches of the Arno river and Florence, his main objective. Kirkman had by this time decided that the valley of the middle reaches of the Arno river offered his corps only very poor possibilities: it was unsuitable for an armoured thrust, and was being held with skill and determination by the LXXVI Panzerkorps, although the inexperienced 715th Division was not performing well in the Chianti mountains. Kirkman therefore decided on 20 July to concentrate the effort of the XIII Corps on the South African 6th Armoured Division’s front so that the corps could make a powerful thrust to seize the crossings over the Arno river in Florence and to the west of the city. To achieve this end Kirkman decided to bring the New Zealand 2nd Division out of reserve and into the line between the South Africans and the Indian 8th Division as part of the relief of the Corps Expéditionaire Français. The New Zealanders were to drive north along the axis from San Casciano on Highway 2 to the crossings of the Arno river lower reaches at Signa, 5 miles (8 km) to the west of Florence.

The South African 6th Armoured Division was to continue its advance from Radda to Impruneta via Greve, with the 4th Division on its right.

On the flanks of this two-pronged thrust the British 6th Armoured Division, in the valley of the Arno river’s middle reaches, and the Indian 8th Division, in the Elsa river valley, were to advance as opportunity offered.

This revision of the basic scheme required some changes in the plan to relieve the Corps Expéditionaire Français. On 21 July the New Zealand 2nd Division moved a brigade forward ready to pass through the right flank of the Corps Expéditionaire Français, and the Indian 8th Division moved up north of Poggibonsi through the centre and left of the Corps Expéditionnaire Français. Much of the XIII Corps' artillery, which now included both 1st and 6th Army Groups Royal Artillery, was divided the better to operate on a front now some 40 miles (65 km) wide. Two medium regiments and one self-propelled gun regiment were placed under command of the New Zealand 2nd Division, one medium regiment under the South African 6th Armoured Division, and one medium regiment under the 4th Division. The Indian 8th Division received one self-propelled gun regiment and the British 6th Armoured Division one field artillery regiment. The 1st and 6th Army Groups Royal Artillery retained two heavy and two medium regiments.

The South African 6th Armoured Division continued its advance from Monte San Michele (Pt 892) on 21 July against stiffening resistance. With its two infantry brigades forward, the division pressed on toward the high ground of Monte Fili (Pt 554) just to the south-west of Greve. The approaches were heavily mined, and a number of supporting tanks were lost to these. Even so, the division had taken most of the high ground, except Monte Fili itself, by 22 July. Another attack with the support of the division’s whole artillery strength followed in morning of 23 July. This was successful, but the I Fallschirmkorps counterattacked throughout the day before withdrawing during the night of 23/24 July. Brigadier J. P. A. Furstenburg’s South African 11th Armoured Brigade passed through and thrust toward Mercatale on the following day in the face of strong rearguards of Faulenbach’s 356th Division supported by PzKpfw VI Tiger heavy tanks. At dusk on 26 July the brigade entered Mercatale, but was then halted on the Greve river by units of 4th Fallschirmjägerdivision on the right of 356th Division.

Meanwhile the New Zealand 2nd Division on the left of the South African 6th Armoured Division was beginning to exert strong pressure on the Germans. Stubbornly opposed by the 4th Fallschirmjägerdivision, which was well supported by artillery, mortars and, on occasion, Tiger tanks, the New Zealanders nonetheless advanced to Tavernelle on Highway 2. The town was in New Zealand hands by 23 July. Continuing their advance on 24 July, the New Zealanders reached the area of Fabbrica, which the Germans were holding stubbornly. Outflanked by the advance of the South African 6th Armoured Division toward Mercatale, however, the paratroopers withdrew during the night of 24/25 July to a new delaying position which, in their sector, covered San Casciano on Highway 2.

On the XIII Corps' eastern flank, the advance of the British 6th Armoured Division, commanded from 24 July by Major General G. W. R. Templer after Evelegh’s reassignment as Assistant Chief of the Imperial General Staff, lagged behind that of the rest of the corps as its axis was dominated by the slopes of the Pratamagno massif. The 4th Division, which was attempting to clear the western bank of the Arno river, entered San Giovanni on 23 July, but the LXXVI Panzerkorps was still largely in control of the situation and the 4th Division found it difficult to develop its subsequent operations against Figline.

On the XIII Corps' western flank, the advance of the Indian 8th Division to the north of Castelfiorentino met little opposition until 25 July, when the division was checked by the 29th Panzergrenadierdivision of the I Fallschirmkorps, which held positions between Montespertoli and Cambiano in the Elsa valley.

On 26 July Generalfeldmarschall Albert Kesselring, the Oberbefehlshaber 'Südwest' and commander of Heeresgruppe 'C', signalled the Oberkommando der Wehrmacht about the excellent performance of the I Fallschirmkorps despite great summer heat against an opponent with overwhelming air and artillery superiority. While generally in agreement, the 14th Army nonetheless stressed the fact that the corps' strength had been severely depleted by casualties and heat exhaustion. Schlemm was authorised to pull back into the 'Paula-Linie' (i) defences during the night of 26/27 July, and to help him fulfil the instruction that this was to be held for several days, the flanking XIV Panzerkorps assumed responsibility for part of Schlemm’s sector.

Lemelsen reckoned that the battle for Florence had now opened in earnest, and the progress of the battle was closely followed by Kesselring, who believed that the 8th Army attached great importance to the capture of the city.

The South Africans, New Zealanders and Indians followed up Schlemm’s withdrawal and by the evening of 28 July were in contact with the 'Paula-Linie' (i) over most of the front. The 4th Division was allocated the difficult task of clearing the Scalari massif, which gave excellent observation over the south-eastern approaches to Florence. Advancing from Dudda on the southern side of the feature on 27 July, Brigadier A. G. W. Heber-Percy’s 12th Brigade gained the southern slopes, but Brigadier C. A. M. D. Scott’s 28th Brigade was checked. Next day neither brigade was successful, so the 12th Brigade’s reserve battalion was brought forward with orders to pass through and clear the summit. The 6/Black Watch attacked on 29 July and after fierce fighting succeeded in reaching the summit and consolidating its hold on Monte Scalari during the night of 29/30 July.

As this feature lay on the boundary between the 14th Army's I Fallschirmkorps and the 10th Army's LXXVI Panzerkorps, its loss led to considerable confusion in the German command structure. The loss also breached the 'Heinrich I' outcrop of the 'Heinrich-Linie' defences, into which Herr had pulled back his right wing on the night of 26/27 July.

Extending along the northern side of the Arno river from a western terminus on Italy’s west coast where the Arno river debouches into the Ligurian Sea, toward Florence and then round the north of this city before turning to the south-east along the Pratomagno massif to Subbiano on the upper reaches of the Arno river, and thence to Senigallia on the Adriatic Sea as its eastern terminus, the 'Heinrich-Linie' was designed the further to check an Allied advance to the north and thereby provide greater time for the completion and manning of the 'Gotisch-Linie'.

The German local withdrawal on 29 July allowed the South African 6th Armoured Division to move forward along the eastern bank of the middle reaches of the Arno river. During the same two days, the New Zealand 2nd Division, which had crossed the Pesa river without opposition on 27 July, tried to clear the higher ground to the north of Cerbaia and San Casciano, but these were outposts of the 'Paula-Linie' (i) and stubbornly defended.

By now, Kirkman had decided he must mount a fresh corps-level attack for which the South African 6th Armoured Division and New Zealand 2nd Division would be best placed to undertake the final thrust through the 'Paula-Linie' (i) to reach Florence. The 4th Division on the right and Indian 8th Division on the left would protect the flanks of this primary thrust, with the British 6th Armoured Division advancing as opportunity offered.

Kirkman issued his orders for the attack late on 29 July. The New Zealand 2nd Division was to carry out the main assault as 'Plonk' proper with the task of reaching and taking the dominating heights of Poggio al Pino and La Poggiona on the far side of the Pesa river. To give the assault greater weight, the Indian 8th Division was to take over the western third of the the New Zealand 2nd Division’s sector. The New Zealand 2nd Division’s attack was to be supported by a heavy artillery effort in which the artillery of South African 6th Armoured Division and Indian 8th Division, as well as 1st Army Group Royal Artillery, were to take part, the last with the responsibility for co-ordinating counter-battery fire. Thus one heavy regiment, the greater part of two medium regiments, two heavy anti-aircraft batteries and two field regiments were to be used in addition to the four field regiments which were already under the command of the New Zealand 2nd Division. On the New Zealand 2nd Division’s right, the South African 6th Armoured Division was to neutralise the German forces occupying the high ground to the west of Impruneta, and also prepare to take over the clearance of Highway 2 into Florence.

The single Indian, New Zealand and South African divisions were in effect to execute a half right wheel along the line of the Pesa river to converge on Florence from the south-west.

The New Zealand 2nd Division regrouped during the night of 29/30 July, and the Indian 8th Division moved up to the Pesa river on its left. The New Zealanders were now deployed on a three-brigade front: Brigadier H. G. Kippenberger’s New Zealand 5th Brigade facing Faltignano, Brigadier W. B. Thomas’s New Zealand 4th Armoured Brigade opposite La Romola and Brigadier J. T. Burrows’s New Zealand 6th Brigade in San Michele. The New Zealand 5th Brigade started its attack at 22.00 on 30 July, with the New Zealand 4th Armoured Brigade following three hours later. By 12.00 on 31 July both Faltignano and La Romola were in Allied hands. The heavy artillery support given to the attack had resulted in a temporary ammunition shortage, and Kirkman agreed to a 24-hour pause to that more ammunition could be brought up from the supply dumps near Lake Trasimeno.

The I Fallschirmkorps was also facing a shortage of ammunition, the Germans fuel poverty having prevented resupply. On 28 July, when high casualties were reported, Lemelsen had informed Kesselring, in his capacity as commander of Heeresgruppe 'C', that Schlemm could continue to hold the 'Paula-Linie' (i) only if received reinforcements, which the 10th Army did not have. As an alternative, Lemelsen was authorised on 29 July to shorten his front in concert with the widening of the 10th Army's front, and though he was still under orders to hold the 'Paula-Line' (i) position, Schlemm was authorised on 30 July to look for a fallback position closer to Florence. On 31 July Adolf Hitler ordered that none of the bridges over the Arno river in Florence was to be blown without his express authorisation, but Kesselring informed Lemelsen that he was to prepare the demolition of all the bridges except the Ponte Vecchio in 'Feuerzauber' (iv).

Despite German fears, the Allies had no intention of fighting in Florence, and on 28 July Kirkman gave conditional orders for his divisions to bypass the city. As Kirkman put it, '…If the enemy does not destroy the bridges and thus carries out his declared policy to treat Florence as an open town, it is desirable that as far as possible Div[vision]s should cross by the most easterly and westerly bridges and pass through the outskirts of the town, so as to give the enemy as little excuse as possible for shelling the place…In the event of all bridges being destroyed, including those in Florence, and Florence itself being held, it is my intention that the [British 4th Division] and [New Zealand 2nd Division] should attempt to secure a crossing outside Florence within their div[isional boundaries], [the South African 6th Armoured Division] probably confining itself to containing the enemy holding Florence.'

During 31 July and 1 August Air Vice Marshal W. F. Dickson’s Desert Air Force attacked the German positions in front of the New Zealand 2nd Division, flying about 100 fighter-bomber sorties on each day.

The attack was resumed 11.00 on 1 August, the New Zealand 2nd Division making simultaneous assaults with its three brigades. Both the New Zealand 4th Armoured Brigade on the right and the New Zealand 6th Brigade on the left made significant progress, and by dawn on 2 August La Poggiona and Poggio al Pino were under close attack. At 06.00 on 2 August the New Zealand 22nd Motor Battalion of the New Zealand 4th Armoured Brigade, supported by a heavy artillery bombardment, cleared the Germans from La Poggiona.

The I Fallschirmkorps, which had pulled out of the 'Paula-Linie' (i) during the night of 31 July/1 August, reported on the following day that the artillery battering had inflicted severe losses, and that in some of its battalions the companies could muster as few as 10 men. With Kesselring’s approval, Schlemm accordingly withdrew that night into a bridgehead position on the line of the Ema river, and on the following night the bulk of his troops crossed the Arno river.

On the right of the New Zealand 2nd Division, the South African 11th Armoured Brigade had cleared Poggio alle Carraie in the evening of 2 August, and at the same time elements of this brigade and the 24th Guards Brigade, moving up from Strada in Chianti, converged on Impruneta, which the Germans abandoned during the night. Throughout 3 August strong columns of the New Zealand 2nd Division, South African 6th Armoured Division and British 4th Division fought their way toward Florence, the New Zealand 5th Brigade heading for Giogoli and the South Africans for Galluzzo. German rearguards made a brief stand at Galluzzo before withdrawing completely during the night of 3/4 August, allowing the New Zealand and South African advance guards to move cautiously through the southern outskirts of Florence. By dawn on 4 August they had reached the Arno river, where they found all the bridges destroyed with the exception of the Ponte Vecchio, which was too narrow and weak to take military traffic and had been blocked at each end by the demolition and mining of nearby buildings. By the end of 5 August the whole southern bank of the Arno river between Florence and Montelupo was in Allied hands, the Indian 8th Division having moved up to the river between Signa and Montelupo.