The battle of the Trigno (27 October-4 November 1943) saw the Eighth Army overcome the second of a series of German defensive positions on the Adriatic coast of Italy, in the aftermath of the initial landings in the south.
The invasion began with an Eighth Army landing at the tip of Calabria on 3 September. This was followed by another Eighth Army landing at Taranto and the Fifth Army landing at Salerno on 9 September. The Salerno beachhead was subjected to a serious German counterattack, but this was eventually defeated, and the Fifth Army advanced to the Volturno Line, the first of the many German defensive lines in Italy. This followed the Volturno in the west and the Biferno in the east.
On the Adriatic coast the Eighth Army had penetrated the German defences on the Biferno at the start of October, but Montgomery then requested permission to pause while he sorted out his lines of communication. This gave the Germans time to retreat to the Trigno, and to reinforce the defences of the Adriatic coast. These troops were formed into the 76th Panzer Corps, under General Herr. The 16th Panzer Division was on the coast, with the 1st Paratroop Division next in line, followed by the 29th Panzer Grenadier Division and finally the 26th Panzer Division on the right, beyond the Trigno valley. The Eighth Army advance had forced the Germans to move three divisions across to the Adriatic to support the paratroops, but they now had a good defensive position in mountainous territory.
Montgomery reorganised his army after the battle of the Biferno. For that battle 13th Corps had been made up of the 1st Canadian Division on the left and the 78th Division on the right, and was placed in the lead. The 5th Corps had the 5th Division and 8th Indian Division and was on the left-rear, guarding the flanks of the advancing 13th Corps.
Montgomery now gave the coastal front to 5th Corps, which kept the 8th Indian Division and gained the 78th Division and 4th Armoured Brigade, veterans of the fighting on the Biferno. 13th Corps was placed on the left to guard the sector from Larino to the Matese mountains. It kept the 1st Canadian Division, and gained the 5th Division, which was inserted into the front between the Canadians and the 78th Division. 13th Corps would face the 26th Panzer Division in the mountains, while 5th Corps had the task of breaking through the German defences, reaching Pescara and then threatening Rome from the north east. However October saw the start of a period of very heavy rain, which caused rivers to rise and turned the ground to mud, making all offensive operations much more difficult
The German defences on the Trigno were a continuation of the Barbara Line, taking it from the upper reaches of the Volturno, across the spine of the Apennines and along the line of the river. However the battle was conducted almost entirely separately on each side of the Apennines. Near the east coast there was a flood plain across the river, and the Germans held the ridges to the west of the plain. Further inland the river ran through a steeper valley.
There was about a 10-12 mile gap between the Biferno and the Trigno, which required a number of preliminary operations to secure. 56 Recce and the Royal West Kents took Montecilfone, ten miles to the south-wet of Termoli. The Recce then took Montenero, five miles to the north west. On the coast the Irish Brigade pushed out patrols as far as Petacciato, two thirds of the way between the two rivers. The Irish then captured Petacciato village on the night of 19-20 October, and followed this up with the capture of Petacciato ridge, to the south-west. Early on 23 October the 1st Royal Irish Fusiliers attempted to capture a bridge over the river, but it was blown before they reached it. The Irish were still able to get across the river and establish a narrow bridgehead. On the coast the 2nd Lancashire Fusiliers also established a bridgehead over the river.
The next major attack was planned for 3 November. It would be preceded by diversionary attacks by 13th Corps in the mountains and the 8th Indian Division. The 36th Brigade, supported by the 6th Inniskillings and tanks from the 46th Royal Tank Regiment, 23 Armoured Brigade, would attack towards San Salvo. On the coast 11 Brigade would attack San Salvo railway station on the coastal railway. The Navy would bombard Vasto, three miles up the coast.
In the mountains the Canadians were ordered to attack west/ north-west from Vinchiaturo towards the communications centre of Isernia, moving along a large valley in the heart of the mountains. By 24 October the Canadians had taken Colle d’Anchise, to the north of the valley, and Bojano, to the south. By 27 October they had cleared the area between Molise and Torella, to the north of the valley. The Germans withdrew to a new position at the western end of the valley, running north from Cantalupo. On 29-30 October the Canadians attacked towards Cantalup, which fell on 30 October. The Canadian advance left Isernia untenable. The Germans pulled out on 4 November, just as the 13th Brigade was planning to send the Wiltshires to attack into the town. On the night of 4-5 November a patrol from the Inniskillings beat them into the town, and to make it clear painted the regimental badge on every available surface. The Wiltshires arrived soon afterwards, to find the town already in Allied hands. Shortly afterwards an American patrol from the Fifth Army entered from the south, also expecting to be first into the town, but finding themselves third.
Ten miles to the left of the main attack the 8th Indian Division was given the task of taking Tufillo, a dramatically placed hilltop village to the west of the Trigno. This was defended by the 3rd Parachute Regiment, and the first attack, on the night of 1-2 November, was repulsed. A second attack early on 3 November was repulsed, as was a night attack on 3-4 November. Tufillo was finally abandoned by the Germans on the night of 4-5 November after their position at San Salvo collapsed, and the village was taken by the Indians on 5 November. Three miles to the south-west another part of the division took Celenza without any problems.
The main attack began on 2 November with a naval and artillery bombardment of the 16th Panzer Division position. On 3 November the 5th Buffs and 6th Inniskillings attacked towards San Salvo, and hit the boundary between two German battalions. The village had fallen by noon. The station took longer to take, but by the end of the day the Germans had decided to pull back towards Vasto. On the night of 3-4 November the West Kents were held up by a German rearguard west of San Salvo, but the Argylls then forced the Germans to retreat. A German attempt to hold Vasto failed, and they had to retreat to the Sangro. The 78th Division reached the Sangro by 9 November. The division held a line from Paglieta to Monte Calvo. On the left the 8th Indian Division wasn’t quite as far forward, with brigades at Atessa, Gissi, Castiglione and Torrebruna, in the mountains between the Trigno and the Sangro.
These successes forced the Germans to pull back to the Sangro, just a few miles short of the eastern end of the Gustav Line. The defences along the Sangro are sometimes seen as part of the Bernhardt Line and sometimes as the outlying elements of the Gustav Line itself, but in either case the Eighth Army would have to fight hard to get through them. The 78th Division followed up, and reached the Sangro by 8 November, but wet weather intervened, and there was another pause in the fighting.