Late in the afternoon the enemy's pressure on the 8th Londons grew almost intolerable, and little by little he was working his way into Tergnier. It was therefore decided to vacate the position, and after dusk the 8th Londons fell back on to the Vouel line, which they extended to the right from the Viry-Tergnier Road as far as the railway. The two companies in Tergnier were ably extricated by their commander and managed to get clear across the Oise, joining the garrison at Condren, which had not been attacked.
The Vouel line was now the most advanced position, and at 6.30 p.m. the Headquarters of the 3rd, 2/4th and 8th Londons were withdrawn from it to Noureuil. The night passed without any further attempt on the enemy's part to advance, and on our side a good deal of patrolling activity took place. This led to several encounters with small parties of enemy, and resulted in the collection of a quite useful bag of German prisoners as well as a machine-gun and team. Under cover of darkness also touch was regained with the Condren garrison.
Information was received on the evening of the 22nd that French troops were rapidly advancing to our assistance, and that they would be ready to counter-attack the next morning with the object of retaking the Crozat Canal line.
On the 23rd March mist appeared yet once more, considerably hampering our defence and giving the enemy an opportunity of massing for attack. Shortly after 8 a.m. the French attack was launched by two battalions of the 125th French Infantry which passed forward through the Vouel line. The result of the attack is not definitely known as it was impossible to see beyond a radius of about 15 yards. It is certain, however, that it failed to reach Tergnier, and by 11 a.m. the French advance was broken and the troops beginning to drift back into our lines. It should be pointed out in fairness to our Allies that they had been rushed up into the line, incomplete in equipment and transport, and that they were called on to operate without previous reconnaissance over ground which was shrouded in mist and unknown to them. On the extreme left the withdrawal was conducted in some disorder, and it was reported that the 18th Division on our left was also being forced back through Frières Wood. The Vouel line, unfinished and shallow as it was, was already occupied to its fullest capacity, and the French falling back on it caused considerable congestion in the well-dug parts. About the same time the German artillery, which had been plastering the Vouel line fairly steadily all the morning, lifted, and was at once succeeded by an accurate and intense machine-gun barrage. This further tended to create difficulty in the position, for in view of the congestion of the trench it became very hard to get orders along, while work on the gaps between the well dug portions was almost impossible.
Shortly afterwards the mist cleared and the awkwardness of the situation became more apparent. The 18th Division were being pressed back towards Villequier-Aumont, and the left flank was entirely in the air, while the constant pushing of small highly trained bodies of the enemy was enabling them to progress along the Oise marshes on the right. Vouel itself was strongly occupied, and troops were massing for attack. By 12 noon the position was no longer tenable. The enemy was advancing frontally and from both flanks, and Lieut.-Col. Dann ordered a withdrawal on to the Green line. This was a partly dug position which formed a portion of the Rear Zone and was held by troops of the 6th Dismounted Cavalry Brigade and the 18th Entrenching Battalion, on a line east of Noureuil and Viry-Noureuil from the St Quentin Canal to the Vouel-Villequier Road. The withdrawal to the Green line from the Vouel position averaged about 1500 yards, and so hard were the enemy pressing that some platoons had to fight their way back. An attempt was made by the French machine-gunners in the Vouel line to cover the Battalion's withdrawal, but this was not effective and, together with several of our own men, they were captured.
The situation was now critical. The falling back of the 18th Division on the left revealed a gap between the Vouel-Villequier Road and Frières Wood of which the enemy was not slow to take advantage, and there appeared every likelihood that the 173rd Brigade would be cut off from the 18th Division and rolled up against the St Quentin Canal. To meet this threat the left flank of the Green line position, consisting of troops of the Dismounted Brigade and details of the 8th Londons, was thrown back and extended towards Villequier-Aumont in an attempt to gain touch once more with the 18th Division. This line was thin, and under the continued German pressure it suffered severely. During the afternoon the enemy thrust south again and entered Noureuil, thus driving a wedge behind the flank of the Green line troops. A glance at the map will show that a further withdrawal was inevitable if the whole Brigade was not to be rounded up. This began about 6 p.m. and the troops, including all that was left of the fighting ranks of the 2/4th Londons, about 120 all told under Capt. Askham, fell back to a position west of Viry-Noureuil, which village was yielded to the enemy.
During the afternoon, while the fate of the bulk of the Brigade was still in the balance, and it was obviously imperative to check the enemy's advance into Chauny by all available means, the Brigadier ordered Major Grover of the 2/4th Londons, who was at Chauny with battle surplus, to organise all available details for the defence of the town. With remarkable skill and despatch Major Grover collected a heterogeneous force of clerks, cooks, officers' servants, transport drivers—anyone who could hold a rifle—and by dusk reported himself in position on the eastern outskirts of Chauny with a force of 10 officers and 270 other ranks at his command. Of these, 2 officers and 54 other ranks were of the 2/4th Londons. This very brilliant piece of work no doubt did much to save the situation, and "Grover's Force" beyond question deserves to rank high among the various similar "scarecrow armies" which these critical days produced.
During the afternoon Lieut.-Col. Dann was attached for duty to Brigade Headquarters, and the remains of the 2/4th and 8th Londons came under command of Lieut.-Col. Derviche-Jones of the latter Battalion.
The withdrawal from the Green line to the River Helot position was considerably impeded by the French troops who were streaming in a westerly direction, and Brigade therefore endeavoured to ascertain what the intentions of the French Commander were. These were found to be to hold a line from Viry-Noureuil to Villequier-Aumont, and accordingly it was decided that the whole of the 173rd Brigade Group should be withdrawn and reorganised in positions to support the French. This reorganisation was successfully carried out. In view of the rapid and confusing moves which had followed each other in such quick succession, it may be well to state in detail the Brigade positions at dawn on the 24th March: