Main German retreat to the Hindenburg Line begins

On 14 March 1917 the morning reports from the front of the British Fourth Army, south of Bapaume, were routine: the German lines appeared to be manned, and some artillery had fired during the night. During the day, however, smoke appeared over St Pierre Vaast Wood, in the former forward salient of the German front. A forward artillery observer of the Guards Division crossed no man’s land and found that the first German trench on that sector was empty. In the afternoon patrols also entered the trenches at Sailly-Saillisel, and the 8th Division found the front line east of Rancourt abandoned. The British Battles Nomenclature Committee later took this day as the start of the German retreat to the Hindenburg Line, reckoned from 14 March to 5 April 1917. The first stage of the retreat, on the river Ancre, had then already been going on for three weeks, but now the whole front from around Arras to Soissons was to be set in motion.

A German timetable

The Germans were acting according to a plan codenamed “Alberich”, prepared by the staff of the army group of Crown Prince Rupprecht of Bavaria as precisely as a mobilisation plan. From 9 February, for 35 days, materials and guns were carried away and a belt of land between the existing front and the new position, the Siegfriedstellung, was destroyed. The last “Alberich day” was 15 March. 16 March was the first of the “marching days”, on which the infantry was to break contact with the enemy and move to the new line: on the wings within two days, in the middle of the arc within three, and on the short sector between Saint-Quentin and La Fère within four.

The plan could not everywhere be carried out to the day. Under British pressure the German 1st Army had already withdrawn from the Ancre on the night of 22/23 February, and on the night of 11/12 March it abandoned the central sector of the next position, at Loupart Wood. Rupprecht was satisfied. “I am completely convinced that we shall reach the Siegfriedstellung too without great difficulty,” he wrote. On 14 March itself his headquarters moved to Mons in Belgium, far behind the new line. That same day a squadron of cuirassiers near Bapaume was ordered to leave plenty of horse manure by the wells. The wells were to be polluted at the last moment before leaving. According to the British official history the order to pollute the wells was certainly given, although it is not known how high in the hierarchy it originated.

The Allies knew more and more about the plan. On 13 March the British found in a dugout in Loupart Wood orders of the German 1st Guard Reserve Division, among them an order of 5 March which for the first time revealed the procedure for the retreat: with three “marching days”, strong rearguards and a final stage of passing through the troops already holding the new position. What they did not know was that the order had meanwhile been changed, and staffs counting the days drew different conclusions from it. Some concluded that the first marching day had already passed.

The failed attack on Bucquoy

This haste had its price. The commander of the British V Corps, General Edward Fanshawe, had planned an attack on the village of Bucquoy, a strongpoint on the northern wing of the Fifth Army, for 15 March. When he concluded that the Germans might abandon it themselves at any moment, on the afternoon of 13 March he ordered an attack that same night. The commanders of both divisions, the 7th and the 46th, protested: patrols had found the garrison alert and the wire thick, and one of the brigades was on a training ground a dozen or so kilometres away. The attack was only moved from 11.45 p.m. to 1 a.m. on 14 March, so that the moon could help, but the sky clouded over. The battalions, which after a march in the rain had barely managed to form up, found no gaps in the wire. A few groups got through the wire but had to turn back once their grenades were used up. The two brigades lost 574 killed, wounded and missing. Three days later the Germans abandoned Bucquoy without a fight.

The French and the dispute with Nivelle

The retreat was also to take in the front of the French Northern Army Group of General Louis Franchet d’Espèrey, which held the arc between Roye and the Aisne valley, with Noyon at its furthest point. Franchet d’Espèrey was preparing an attack here between the Oise and the Avre, subsidiary to the great offensive on the Aisne. As early as 4 March, seeing signs of German preparations, he proposed striking as soon as possible, to catch the Germans in the middle of their retreat. The French commander-in-chief, General Robert Nivelle, replied on 7 March that he saw no sure signs that the retreat would include this sector, and refused to change the plan. He allowed only a limited attack on the first position to be prepared. On 11 March Franchet d’Espèrey ordered it to be prepared, with a 36-hour bombardment due to begin on 17 March. The British official history considers that Nivelle’s veto may have cost the French a great success.

Meanwhile the Germans stopped repairing their trenches and wire, their artillery replied weakly, columns of smoke rose over a dozen or so villages, the roads around Noyon were flooded by water from breached dykes, and railway bridges were blown up. On the night of 12/13 March French patrols entered the German trenches in several places. Between 7 and 13 March Nivelle, too, became convinced that the Germans were falling back to the Hindenburg Line. Yet when on 13 March he met Field Marshal Douglas Haig at the conference in London, he declared that the main attack on the Aisne would go ahead unchanged.

15 and 16 March

Over the next two days the British followed the Germans cautiously, from trench to trench. Resistance came only from snipers and single machine guns. Small patrols first checked whether a trench was empty, and only then did larger units occupy it. On the evening of 15 March news reached Haig that south of the Somme too the Germans had thinned out their front and were holding it only with machine-gun rearguards. By the evening of 16 March the Fourth Army had occupied the whole of St Pierre Vaast Wood except its north-eastern corner, and the western part of the wood near Moislains. On the French front, by the evening of 16 March Franchet d’Espèrey’s troops had occupied the whole German first position in the middle of the arc. Sappers of the British 48th Division were already towing pontoons at night along an ice-bound canal to throw a bridge towards Péronne.

16 March was the first marching day. On the night of 16/17 March the German rearguards abandoned the next position on the Fourth Army’s front, and the main forces were already marching towards the Hindenburg Line. British patrols that night still met machine-gun fire and grenades, but before dawn on 17 March it turned out that along the whole front of the Fifth Army and on the right wing of the Third Army the Germans were gone. Haig ordered a general advance along the whole front from the Roye road to south of Arras. The real retreat had begun.

What came next

Over the next few days the Allies entered Bapaume, Péronne, Roye and Noyon. By 19 March the main German forces had occupied the new position, shortening the front, according to the British official history, by 25 miles, about 40 kilometres, and saving 13–14 divisions. Haig feared that the whole operation might be a prelude to a German counter-attack, and ordered the enemy to be pursued cautiously, by small detachments. Nor did he change his plans: preparations for the offensive at Arras went on. The Allies were recovering a belt of French land in places several dozen kilometres wide, but turned by the Germans into a desert.