In the chaos of the retreat of 11th Suffolk at Erquinghem, the Battalion lost its most heroic of members.
As the battalion fell back to the river, those not wounded formed a defensive line with their backs to the water. On the left flank, closest to Armentiers itself, a small pocket of men from 'D' Company held on courageously. Just as they prepared to retire, they were met with a hail of fire, causing a great man casualties.
One of those men who was to be wounded was Lance Corporal Sid Day, who had just eight months before, won the Victoria Cross at Malakhoff Farm. Shot through the right hand, as Day fumbled in great pain to apply his field dressing, the enemy came on and he was taken prisoner. He was now 'in the bag'.
Day, who had been serving with 14 Platoon  in 'D' Company, had his hand treated to before he and his colleagues were sent by train to Germany, where in due course, they found themselves at their new home at Langensalza PoW camp near Leipzig. 
At first, he was listed as missing and it was not until June 1918 that he news was finally received from him and he was officially listed as a prisoner of War. Day was like many of his fellow 'caged birds' depressed by the thought that the Germans had them onto run in April, but as the weeks wore on, trapped in their camp, they were oblivious to the fact that German was exhausted. Their planned last great thrust in the west had achieved only partial success and though great amounts of Allied prisoners had been taken, these additional mouths to feed were a real burden in a country now on a strict system of rationing, where meat was only on the menu in restaurants two days a week.
For Day, life in the camps was an unending round of cheerful concerts, party games, and the usual daily working parties. At an all English pageant held in the camp theatre, Day took the part of a glorious war hero with much gusto. His fellow comrades made for him, a replica VC from the zinc lining an old tea chest, which he proudly wore during the show (above). 
Soon, they knew, the tide would turn.

By 3.15 pm, on the afternoon of 10th April 1918, the enemy onslaught had been checked by the men of the 11th Battalion south of the river Lys at Erquinghem and the line had been completely re-established between the original position (near Bac St. Maur) and the right Coy in Erquinghem Switch Trench. Holding on valiantly, by 3.30pm, an order was received that they were to retire to positions north of the river Lys.
The 9th Northumberland Fusiliers on their left, sent a message to Colonel Tuck that they would need some two hours to retire. Tuck therefore decided to hold his Battalion in place as long as possible to allow them to retire. His decision though gallant, led however to more casualties being inflicted on the Battalion during this time.
“The Battalion held off repeated attacks of the enemy until 5.00pm, when the troops on the left had withdrawn”. Now alone and fighting valiantly on three sides, before seeing that they were alone, the CO gave the order to retire.
Crossing the river with what remained of a broken bridge, most of the men stripped off and swam the river, leaving their equipment and gas masks behind. The wounded were left helpless on their stretchers along the banks as Private Frank Hornesy recalled: "Clothes and equipment also lay everywhere here which only too plainly told us if we wanted to go on there was only one way and that was to swim. Some badly wounded chaps lay on stretchers. They had been carried as far as possible. They needed help by they had to be left. We we're the extra stragglers of the retreat. Perhaps we had been sacrificed on purpose to try and hold the enemy if only for a few hours. I don't suppose we were expected to be alive by this time if the truth was known. Lower down several men could be seen swimming through the dark cold water. Many were drowned while attempting to swim this canal. We must soon think about it. Bill was cursing. Just then a violent burst of machine gun fire broke out not many hundred yards away from us. The Germans were in the village we had just left. That decided us who wanted to stop to be taken prisoner or killed. Let them stop who like - we were going through the water".
Stripping down to the bare minimum in the middle of a battle, Hornsey and his chum Bill got ready to cross: "I slung my rifle on my back, discarded my gas mask, put my wallet in a waterproof ammunition case and walked into the water, Bill following me. We were soon in deep water, the current very strong. Thank goodness we could both swim well. My clothes hung like lead. Once again I was almost giving up when my feet touched the bottom and we waded out".
​The remains of the Battalion re-grouped in the vicinity of a hamlet called Waterlands where it formed a defensive square, preparing to fight on all fronts. Patrols were sent to the north-west and soon it was established that the enemy were in strength pressing further north along the cover of the railway line on the Battalion’s left flank.