21,000 British prisoners were taken on the opening day of the German Spring Offensive. Royal Engineer Thomas Cass was one of them.

There was masses of Germans, they come over like hoards. They come over and overwhelmed us and so I was taken prisoner at 2 o’clock and I was in the German trenches with them until 8 o’clock at night. Then we got up behind the line and they were collecting all the prisoners – the German guards were – and we had to march back to St Quentin, then. I always remember one German soldier, a young chap he was, he was marching by the side of me, and he patted me on shoulder and I’ll always remember what he said. He said, ‘Brave Englander’, he said, ‘brave Englander’ and patted me on the back.

In response to the overwhelming German assault, reserve troops were moved up to help strengthen the Allied line. Charles Templar of the Gloucestershire Regiment had been nearly 20 miles from the front when the bombardment started, but was hurriedly pushed into action.

We marched the whole of that day with a 10 minute halt each hour as usual, until we came within shelling distance of the line, as it was then. That was about nightfall and we were put into huts, sort of big Nissen huts in our various companies. During the night, when we were all asleep, Jerry started shelling the area and he hit the hut which contained most of the ‘C’ Company men and caused a lot of casualties there. So that after that, we were more or less awake.

On 22 March, intense fighting continued as the German attack pressed on. Edmund Williams of the King’s (Liverpool Regiment) was in action that day.

We’d got settled, and about just as it was coming dawn somebody on my left said, ‘They’re attacking.’ This was Germany’s first attack, about half-past six in the morning, the day’s start. So we all lined the trench. I found myself firing rapid rounds as fast as I could into the mists. My little brother was firing his Lewis gun. The machine gun in Roupy was enfilading us quite severely, in fact some of the bullets were coming in – I was just got a bit of traverse – but coming into the trench just behind me. One officer managed to make it back from the number three platoon, he got a bullet through the arm and went down. But that was the only person I ever remember going back.

Despite these attempts to stem the German advance, large parts of the front were given up by retiring British forces. Leonard Ounsworth of the Royal Garrison Artillery outlined his part in this confused and hasty retreat.

As we got into a little bit of order on the retreat the major organised it so that we always had at least two – sometimes four – guns in action by splitting the battery duties into three sections, right, left and centre sections. He would take the retreating section back to a position where they’d to be operative, and then he would go forward again – and I was his personal orderly during that time – he would go forward again to the advance section and pull them out. On one or two occasions we pulled out in face of the enemy – had just a few infantry left to sort of cover us till we got the guns out. And then leap-frog that section over the other two, then come back and repeat the process like that so that he always had some of his guns in action, which meant that there was always some cover for the retreating infantry, some protection from enemy traffic coming up, you see.

For the rest of March, the British were forced back, often in a disorganised manner. NCO Ernest Bryan was among these exhausted and depleted troops.

We knew what the orders were; they must not break through. If retirement, and it will be necessary, retire, but don’t let them break through. That’s all our orders, and that’s what was done, from 21 March, nine days and ten nights of scrapping and retiring, scrapping and retiring round the villages. We got to Ham eventually. That was the biggest town there was there, outside St. Quentin. When we got into there nobody knew anybody. There was no such thing as a battalion. We were a nondescript pile of all sorts of regiments, bits and pieces, anybody at all; sanitary people, cooks, everybody, they were all in it.

The retreating men had to abandon their normal daily routine, finding food and shelter where they could. Alfred Griffin of the King’s Royal Rifle Corps explained how he kept himself fed.

We came back in dribs and drabbles. You just kept together for safety’s sake. We had an officer, up to the time we got to this embankment. We came back here fighting and fighting. We had nothing, never had any rations at all issued to us. All we were doing was, if we saw a dead man the first thing we did was empty his haversack and see what he’d got to eat – we were starving. We’d used up our first rations the first day. We just done what we could. Where we saw a lorry crashed with bully beef and that on, well of course nobody stopped us looting it: we’d have eaten them!

As well as the huge numbers of Allied prisoners taken in the opening phase of the offensive, heavy casualties were suffered. Maberly Esler of the Royal Army Medical Corps described the difficulty of trying to help wounded men amidst the confusion and danger of the fighting.

I remember a sergeant beside me, a shell went up and smoke occurred, as the smoke cleared he was sitting with his two stumps waving in the air, his legs completely shot off, and we said, ‘Well, we’ll take you to the side of the road.’ He said, ‘You’re not going to leave me here?!’ I said, ‘I’m afraid we can’t do anything about it, we’ve got no stretcher-bearers, we’ve got nothing to carry you with, we’ve got nothing to give you, we’ll put you out of the way of the tanks’ – which were following us down the road – ‘so they won’t run over you, and I hope you’ll be picked up.’ It was an awfully painful thing to have to do. People who could walk and were wounded, a lot of people, were helped along; I had about five people clinging to me, one with a jaw blown away bleeding all over me. Getting through that was a miracle really, a miracle. It was like a nightmare.

By early April, the Germans had advanced around 40 miles into Allied territory. Despite this dire situation, British signaller Jim Crow didn’t see men’s morale break.

Well, it was… I don’t know exactly what you did think. Sometimes you thought, ‘Well, we’re doing alright.’ Then another time you was a bit despondent. I don’t know that ever I saw any of the infantry what you might actually term panicking. They’d run back and try and get in some trenches or under a bit of cover. But the morale was really grand, taking it all through. Considering what we were losing.

The Germans launched a second attack, Operation Georgette, on 9 April – further north, in Flanders. Again it opened with a massive bombardment on British lines. Walter Grover of the Sussex Regiment narrowly escaped its effects.

Our post where we were standing, there was a dugout each side. I was on guard at one entrance and another young chap, he was on the other entrance. And one of the German minenwerfers, that was their big mine thrower, the minenwerfer. And it was a great big thing and it fell right onto where this chap was. The explosion, the concussion, fetched the blood from our nose – we were bleeding from concussion – blew us off the fire step. Fortunately we were just suffering from concussion, but this poor chap, it, well… We picked up what pieces were left of him. But it killed most of them down in the dugout. The blast, you see, it went right down and killed most of them then and there.

Intense fighting on that first day led to further German gains and heavy British losses. German gunner Paul Oestreicher witnessed the impact this had on exhausted British prisoners taken in the battle.

We were standing near Armentieres. We had before the attack many weeks of preparations, and were calculating the shooting exactly. This day, we entered Armentieres without practically any difficulties. The day was fighting, with very, very little resistance because the artillery had prepared it extremely well and after a few hours, heaps of prisoners came from the other side. They were in a rather desperate condition and very tired and worn out from the long shooting. They all said nothing else but, ‘The war is over for us and we don’t want to go back any more.’

German gains continued during the next few days. The situation once again looked critical for the Allies. On 11 April, British commander in chief Sir Douglas Haig issued a special order of the day, urging his men to fight on to the last. British private Walter Cook did not think much of it.

There was a thing given out about ‘Backs to the wall’ by the commander in chief but I don’t know where the wall would be. Backs to the sea, I should thing would have been more like it… But morale was not low it was over the old ground again; they weren’t gaining anything. They were only gaining a morass of shell ridden country.

Despite its initial success, Operation Georgette lost momentum and was called off at the end of April. A third phase of fighting began on 27 May, when the Germans attacked along the Chemin des Dames ridge. British officer Sidney Rogerson remembered the opening barrage.

I was actually standing in the mess having a whiskey and soda, when suddenly: whizz plop, whizz plop. Two German gas shells burst right on our doorstep. And within a second, the biggest barrage that I was ever in in the war burst on us. Or rather, we thought it had burst on us, but what the Germans had done on this occasion was to direct the whole weight of their gunfire onto the reserve areas and concentrate their mortars onto the front line, the fighting line. So the casualties among the reserve staff were enormous.

The Allied line was mainly held by the French, although British troops had been sent down for a period of rest. British private George Thompson was wounded in the battle.

As we entered the woods of the Chemin des Dames the bombardment started. Oh, it was a terrific bombardment. We got down into dugouts at first for the worst of it. You see, if they are bombarding you, they can’t attack or they’d be bombarding themselves. So you wait until the bombardment’s subsided and then you come out. When we came out of dugouts we went forward into trenches. We were standing in the trench waiting for the attack to come and we got heavy rifle fire from the left. And I got a bullet through the shoulder, under my chin like that and went through my shoulder. Then another one in beside my spine and out at the side, that got me down. I went down in the trench and the next thing I knew, I was being rolled over by two German soldiers.

As in March and April, the Germans made large gains and inflicted heavy casualties on the Allies. Yet again, British troops had to make a desperate defence in the face of an enemy onslaught. But Ernest Millard of the Royal Field Artillery kept his nerve.

They advanced and they captured ‘C’ Battery of my brigade from the rear and they were at our rear, left rear. So they came in through the woods. There was no question of nerves. I never had any thought of nerves. There was a job to be done, whether it was under fire or not it had to be done, that was a priority. I’d never had any flinching – ‘Oh God, this is awful.’ Nothing like that, nothing ever. There was a job to be done and we just got on with it.Despite huge successes since March, by early June the overall German offensive was faltering.

The German soldiers were exhausted from successive battles and had out-run their supplies of manpower and food by advancing so far and so fast. British signaller George Banton recalled the end of this phase of the offensive.

We retreated day by day and almost invariably Jerry was in that place within 24 hours. But it gradually simmered out. The 19th Division, they went in and they managed to hold up the advance and it gradually petered out. But the Germans had made a very large salient and that might’ve assisted – been partly responsible – for their not proceeding further. It was getting dangerous for them. They’d reached Chateau Thierry and that was as far as they dared go.

The German Spring Offensive delivered stunning successes and nearly succeeded. But ultimately, the advance could not be sustained. For Allied troops, it was difficult to maintain morale as they gave up ground and retreated under fire. Alexander Jamieson of the Royal Scots summed up how he felt as the enemy closed in during the early part of the offensive.

We retired again to what was known as the Green Line. The Green Line was a recently constructed defence trench that was nothing like finished and while we were there the order came along, ‘This position must be held at all costs – to the last man.’ And I felt terrible. I just thought, ‘I’m only 19, I’ve only been here five weeks and apparently I’m going to be killed. And how am I going to be killed..?’

Voices of the First World War is a podcast series that reveals the impact the war had on everyone who lived through it through the stories of the men and women who were there.