Whilst these stirring events had taken place on the right flank, there had been heavy fighting also on the left. Here the British defence had been based upon two small but strong forts, called Cailloux North and Route A Keep. The latter fell early in the action, the German infantry coming upon it so unexpectedly in the fog that the machine-guns were at the moment mounted upon the parapet and elevated for indirect fire. They were put out of action, and the place was surrounded and taken. This greatly weakened the left wing of the defence. Farther still to the left the Germans were pushing through Loisne, and the fort called Loisne Central was heavily engaged. This portion of the line was held by the 166th Brigade. Once the German wave actually lapped over into the little fort, but the place was not taken, and its machine-guns still clattered and flashed. All day the Germans were held at this point though the pressure was great. During the night the 13th King's Liverpools from the 9th Brigade were sent as a reserve to the weary line. At 7.40 on the morning of April 10 the enemy, under cover of a murderous barrage, attacked Loisne once more, striving hard to break in the left of the British defence. The garrison suffered terribly, but none the less the stormers were shot back into their shell-holes and lurking-places. Two successive attacks on the forts of Cailloux and Festubert had no better success and were less strongly urged. At seven in the evening they again, with a sudden rush, got a footing in the fort of Loisnes, and again were driven out, save for twenty-one who remained as prisoners. Another day had passed, and still Lancashire stood fast and the lines were safe. On April 11 the whole position was swept by a heavy shell-storm, and the German infantry clustered thickly in front of the crumbling barricades. The guns both of the Fifty-fifth and of the Eleventh Division played havoc with them as they assembled, so that the attack was paralysed on the right, but on the left the two little forts of Festubert East and Cailloux were both overwhelmed. The former, however, was at once retaken by a mixed storming party from the 5th and 13th King's Liverpools. Late in the evening Cailloux Keep was also stormed, and once more the position was intact.
There was now only Route A Keep in possession of the enemy, and it was determined to regain it. The guns had quickly registered upon it during the day, and at midnight they all burst into a concentrated bombardment which was followed by a rush of two companies, one drawn from the Liverpool Scots and the other from the 13th King's Liverpools. The place was carried by assault, and the garrison held it strongly on the 12th and 13th against a series of attacks. It was a most murderous business, and the brave little garrisons were sadly cut about, but they held on with the utmost determination, having vowed to die rather than give the fort up. The survivors were still there, crouching among the ruins and exposed to constant heavy shelling, when on April 15 the old epic was ended and a new one was begun by the relief of the Fifty-fifth Division by Strickland's First Division. The episode will live in history, and may match in tenacity and heroism the famous defence of Ovillers by the German Guards. The casualties were heavy, but it may be safely said that they were small compared with those of the attacking battalions.
The story has been carried forward in this quarter for the sake of connected narrative, but we must now return to the events of April 9, and especially to the effect produced upon the Fortieth Division by the exposure of their southern flank. This fine unit, with its terrible wounds only half healed, was exposed all day to a desperate attack coming mainly from the south, but involving the whole of their line from Laventie to Armentières. The division, which is predominantly English, but contains one brigade of Highland troops, fought most valiantly through the long and trying day, enduring heavy losses, and only yielding ground in the evening, when they were attacked in the rear as well as in front and flank.
In the morning the Fortieth Division had the 119th Brigade (18th Welsh, 21st Middlesex, and 13th East Surrey) on the right, while the 121st Brigade (20th Middlesex, 12th Suffolks, and 13th Yorks) was on the left, joining up with Nicholson's Thirty-fourth Division which held the Armentières front. The right of the Fortieth was involved in the heavy initial bombardment and also in the subsequent infantry advance, which established a footing in the front trenches of the 119th Brigade. Whilst a counter-attack was being organised to drive the stormers out, it was found that the right and the rear of the position were threatened by the advance through the Portuguese. The 120th Scottish Brigade in reserve was ordered to form a defensive flank, but the 10/11th Highland Light Infantry, the nearest unit, found itself almost overlapped, and the brigade had to fall back upon the bridges at Nouveau Monde in order to protect the river crossings. The 2nd Scots Fusiliers covered the bridge-head, while the whole of the 119th Brigade fell back to the line of the Lys, save only the garrison of Fleurbaix. The 121st Brigade was still holding its line in the Bois Grenier sector. By 1 o'clock the bulk of the Fortieth Division was across the Lys, the bridges being destroyed one by one as the day advanced. The destruction was not in all cases complete, and in that of the Pont Levis at Estaires was absolutely checked by a chance shell which destroyed the leads, and prevented the explosion. The enemy, under cover of machine-guns mounted in the houses of Bac St. Maur, were able to cross the river here and get a footing upon the northern bank. The 74th Brigade from the Twenty-fifth Division and the 150th from the Fiftieth were coming up, however, and it was still hoped that the German advance might be checked. So severe had the fighting been that the 18th Welsh had only 5 officers and 120 men standing in the evening.
The 121st Brigade were in the meanwhile endeavouring to hold the Fleurbaix defences on the left of the line. At 11.30 A.M. the Germans were in the east of the village, but the 12th Suffolks, who formed the garrison, put up a most determined resistance, in which they were aided by a company of the 12th Yorkshires Pioneer Battalion. It was not till 5.30 that the village was nearly enveloped, and the troops had to make their way as best they could to the north bank of the Lys. The 20th Middlesex and 13th Yorkshires, with their flank badly compromised, still held on to the Bois Grenier sector. These battalions on the left were taken over by the Thirty-fourth Division, with whom they were now in close liaison.
On the morning of April 10 the two brigades which had crossed the river were in very evil case, having sustained heavy losses. They were concentrated about Le Mortier. The 74th Brigade was in position south of Croix du Bac in touch on the right with the 150th Yorkshire Territorials. All day the enemy were pushing west and north, but meeting a strong resistance from the British who had an excellent trench, the Steenwerck switch, to help them. Some ground was lost, but much of it was regained in the evening by a spirited counter-attack of the 14th and 10/11th Highland Light Infantry, the 2nd Scots Fusiliers, and the 21st Middlesex, which advanced over 600 yards. The pressure was great and unceasing, however, so that the morning of April 11 found the line farther back again. The two brigades were reduced to about 1000 men, who were concentrated at Strazeele, while the 92nd and 93rd Brigades of the Thirty-first Division came up in their place. A brave counter-attack by the 93rd Brigade at Le Verrier gained its objective, but created a dangerous gap between it and the 92nd Brigade on its right, which was filled, however, by the 11th East Yorkshires. On the 12th the remains of all three brigades were strung out to cover Strazeele and Hazebrouck from the east and south-east, but next day they were relieved by the welcome appearance of the First Australian Division, whose advent will afterwards be explained. It had been a very desperate term of service, in which for three days the sappers of the 224th, 229th, and 231st Field Companies Royal Engineers had to fight as hard as the infantry. The Fortieth, like the other divisions described, were driven back, but only as the buffer is driven back, with the ultimate result of stopping the force which drove it. They were much aided by the guns of the Fifty-seventh Division under General Wray. The losses of the division were 185 officers and 4307 other ranks. When one reflects that the losses on the Somme three weeks before had been equally heavy, one can but marvel.
We shall now follow the fortunes of the Thirty-fourth Division (Nicholson), which was on the immediate left of the Fortieth, covering a sector of 8000 yards, including the town of Armentières. On the north, near Frelinghien, it joined the right of the Twenty-fifth Division. On the night of April 7 the enemy fired an enormous number, 30,000 or 40,000, gas-shells into Armentières, and soaked it to such an extent with mephitic vapours that it became uninhabitable. Otherwise there was no warning of an impending attack, which came indeed as a surprise to all the forces engaged.
On April 9 the division lay with the 103rd Brigade upon the right section and the 102nd upon the left, with the guns of the Thirty-eighth Division behind them. The main attack on this day was entirely upon the two divisions, the Portuguese and the Fortieth, to the south. There was heavy shelling, however, of the back areas, especially Armentières and Erquinghem. When as the day advanced everything on the right had given way or weakened, the 103rd Brigade threw back a long thin defensive line, facing south, which ended in the direction of Fleurbaix. At the same time the reserve 101st Brigade was ordered up to cover Bac St. Maur Bridge. One battalion of the Reserve Brigade, the 11th Suffolks, got into Fleurbaix, when by a happy chance they were able to reinforce their own comrades of the 12th Battalion. These two sturdy East Anglian units held the village in a very desperate fight for many hours. The 15th and 16th Royal Scots of the the same brigade had some hard fighting also as they continued the defensive line formed by the 103rd Brigade, and tried to prevent the victorious Germans from swarming round and behind the Thirty-fourth Division. Some idea of the danger may be gathered from the fact that of two brigades of artillery engaged one was firing south-west and the other due east. The original front was never in danger, but it was a desperate conflict upon the refused flank.