German spring offensive
The German spring offensive, also known as Kaiserschlacht or the Ludendorff offensive, was a series of German attacks along the Western Front during the First World War, beginning on 21 March 1918. Following the American entry into the war in April 1917, the Germans decided that their only remaining chance of victory was to defeat the Allies before the United States could ship soldiers across the Atlantic and fully deploy its resources. The German Army had gained a temporary advantage in numbers as nearly 50 divisions had been freed by the Russian defeat and withdrawal from the war with the Treaty of Brest-Litovsk.
There were four German offensives, codenamed Michael, Georgette, Gneisenau, and Blücher-Yorck. Michael was the main attack, which was intended to break through the Allied lines, outflank the British forces and defeat the British Army. Once that was achieved, it was hoped that the French would seek armistice terms. The other offensives were subsidiary to Michael and were designed to divert Allied forces from the main offensive effort on the Somme. No clear objective was established before the start of the offensives and once the operations were underway, the targets of the attacks were constantly changed, depending on the tactical situation.
Once they began advancing, the Germans struggled to maintain the momentum, partly due to logistical issues. The fast-moving stormtrooper units could not carry enough food and ammunition to sustain themselves for long, and the army could not move in supplies and reinforcements fast enough to assist them. The Allies concentrated their main forces in the essential areas. Strategically worthless ground, which had been devastated by years of conflict, was left lightly defended. Within a few weeks, the danger of a German breakthrough had passed, though related fighting continued until July.
The German Army made the deepest advances either side had made on the Western Front since 1914. They re-took much ground that they had lost in 1916–17 and took some ground that they had not yet controlled. Despite these apparent successes, they suffered heavy casualties in return for land that was of little strategic value and hard to defend. The offensive failed to deliver a blow that could save Germany from defeat, which has led some historians to describe it as a Pyrrhic victory. In July 1918, the Allies regained their numerical advantage with the arrival of American troops. In August, they used this and improved tactics to launch a counteroffensive. The ensuing Hundred Days Offensive resulted in the Germans losing all of the ground that they had taken in the Spring Offensive, the collapse of the Hindenburg Line, and the capitulation of Germany that November.
German preparations
Strategy
The German High Command—in particular General Erich Ludendorff, the Chief Quartermaster General at Oberste Heeresleitung, the supreme army headquarters—has been criticised by military historians for the failure to formulate sound and clear strategy. Ludendorff privately conceded that Germany could no longer win a war of attrition, yet he was not ready to give up the German gains in the west and east and was one of the main obstacles to the German government's attempts to reach a settlement with the Western Allies.Although Ludendorff was unsure whether the Americans would enter the war in strength, at a meeting of the Chiefs of Staff of the German armies on the Western Front on 11 November 1917, he decided to launch an offensive. The German government and Field Marshal Paul von Hindenburg, nominally the Chief of the General Staff, were not party to the planning process. Eventually it was decided to launch Operation Michael near Saint-Quentin, at the hinge between the French and British armies, and strike north to Arras. The main reason for the choice was tactical expediency. The ground on this sector of the front would dry out much sooner after the winter and spring rains and would therefore be easier to advance across. It was also a line of least resistance as the British and French armies were weak in the sector.
The intention was not to reach the English Channel coast, but to break through the Allied lines and roll up the flank of the British army from the south, pushing it back toward the Channel ports or destroying it if the British chose to stand and fight. Further operations such as Operation Georgette and Operation Mars were designed to strike further north to seize the remaining Allied ports in Belgium and France while diverting Allied forces from Michael. However, these remained only secondary and weaker operations, subordinate to Michael.
The constant changing of operational targets once the offensive was underway gave the impression the German command had no coherent strategic goal. Any capture of an important strategic objective, such as the Channel ports, or the vital railway junction of Amiens, would have occurred more by chance than by design.
Changes in tactics
The German army had concentrated many of its best troops into stormtrooper units, trained in infiltration tactics to infiltrate and bypass enemy front line units, leaving these strong points to be "mopped-up" by follow-up troops. The stormtrooper tactic was to attack and disrupt enemy headquarters, artillery units and supply depots in the rear areas, as well as to occupy territory rapidly. Each major formation "creamed off" its best and fittest soldiers into storm units; several complete divisions were formed from these elite units. This process gave the German army an initial advantage in the attack, but meant that the best formations would suffer disproportionately heavy casualties, while the quality of the remaining formations declined as they were stripped of their best personnel to provide the stormtroops. The Germans also failed to arm their forces with a mobile exploitation force, such as cavalry, to exploit gains quickly. This tactical error meant the infantry had to keep up an exhausting tempo of advance. Notwithstanding the effectiveness of the stormtroopers, the following German infantry often made attacks in large traditional waves and suffered heavy casualties.To enable the initial breakthrough, Lieutenant Colonel Georg Bruchmüller, a German artillery officer, developed the , an effective and economical creeping barrage scheme. There were three phases: first, a brief bombardment on the enemy's command and communications ; then, destruction of their artillery; lastly an attack upon the enemy front-line infantry defences. Bombardment would always be brief so as to retain surprise. Bruchmüller's tactics were made possible by the vast numbers of heavy guns—with correspondingly plentiful amounts of ammunition for them—which Germany possessed by 1918.
Allied preparations
Defensive tactics
In their turn, the Allies had developed defences in depth, reducing the proportion of troops in their front line and pulling reserves and supply dumps back beyond German artillery range. This change had been made after experience of the successful German use of defence in depth during 1917.In theory, the front line was an "outpost zone", lightly held by snipers, patrols and machine-gun posts only. Behind, out of range of German field artillery, was the "battle zone" where the offensive was to be firmly resisted, and behind that again, out of range of all but the heaviest German guns, was a "rear zone" where reserves were held ready to counter-attack or seal off penetrations. In theory, a British infantry division deployed three battalions in the outpost zone, four battalions in the battle zone and two battalions in the rear zone.
This change had not been completely implemented by the Allies. In particular, in the sector held by the British Fifth Army, which they had recently taken over from French units, the defences were incomplete and there were too few troops to hold the complete position in depth. The rear zone existed as outline markings only, and the battle zone consisted of battalion "redoubts" which were not mutually supporting.
Operation Michael
On 21 March 1918, the Germans launched a large offensive against the British Fifth Army and the right wing of the British Third Army.File:Bundesarchiv Bild 183-P1013-316, Westfront, deutscher Panzer in Roye.jpg|thumb|German A7V tank at Roye, March 1918
The German armies involved were—from north to south—the Seventeenth Army under Otto von Below, the Second Army under Georg von der Marwitz and the Eighteenth Army under Oskar von Hutier, with a Corps from the Seventh Army supporting Hutier's attack. Although the British had learned the approximate time and location of the offensive, the weight of the attack and of the preliminary bombardment was an unpleasant surprise. The Germans were also fortunate in that the morning of the attack was foggy, allowing the stormtroopers leading the attack to penetrate deep into the British positions undetected.
By the end of the first day, the British had lost 7,512 dead and 10,000 wounded and the Germans had broken through at several points on the front of the British Fifth Army. After two days the Fifth Army was in full retreat. As they fell back, many of the isolated "redoubts" were left to be surrounded and overwhelmed by the following German infantry. The right wing of Third Army became separated from the retreating Fifth Army, and also retreated to avoid being outflanked.
Ludendorff failed to follow the correct stormtrooper tactics, as described above. His lack of a coherent strategy to accompany the new tactics was expressed in a remark to Rupprecht, Crown Prince of Bavaria—commander of one of his Army Groups—in which he stated, "We chop a hole. The rest follows." Ludendorff's dilemma was that the most important parts of the Allied line were also the most strongly held. Much of the German advance was achieved where it was not strategically significant. Because of this, Ludendorff continually exhausted his forces by attacking strongly entrenched British units. At Arras on 28 March, he launched a hastily prepared attack against the left wing of the British Third Army, to try to widen the breach in the Allied lines. In this sector, the British defences in depth were complete and fully manned, some of the opening German bombardment hit only empty positions and there was no fog to give cover to the attacking stormtroopers. After a day, the Germans had achieved only minor gains and had suffered heavy casualties. Operation Mars was immediately cancelled.
The German breakthrough had occurred just to the north of the boundary between the French and British armies. The French commander-in-chief, General Philippe Pétain, sent reinforcements to the sector too slowly in the opinion of the British commander-in-chief, Field Marshal Douglas Haig, and the British government, though the historian Elizabeth Greenhalgh disputes this, arguing that Petain sent the six additional divisions quicker than had been arranged with Haig – in 2 days instead of 4 – and arranging for extra divisions several times – 12 divisions on 23 March and 13 on the 25/26 March – before requests came in from Haig. The Allies reacted by appointing the French General Ferdinand Foch to coordinate all Allied activity in France, and subsequently as commander-in-chief of all Allied forces everywhere.
The success of Operation Michael led German infantry to advance too far from its supply bases and railheads. The stormtrooper units leading the advance carried supplies for only a few days, to avoid being overburdened, and relied on supplies delivered quickly from the rear. The advance was slowed by supply shortages, which gave Allied commanders more time to reinforce the threatened areas and to slow the advance still more. German supply difficulties were made worse by the direction of advance, which crossed the wasteland created during the Battle of the Somme in 1916 and by Operation Alberich, the German retirement to the Hindenburg Line from February to March 1917.
After a few days, the German advance began to falter, as the infantry became exhausted and it became increasingly difficult to move artillery and supplies forward to support them. Fresh British and Australian units were moved to the vital rail centre of Amiens and the defence began to stiffen. After fruitless attempts to capture Amiens, Ludendorff called off Operation Michael on 5 April. By the standards of the time, there had been a substantial advance. It was, however, of little value; a Pyrrhic victory in terms of the casualties suffered by the crack troops, as the vital positions of Amiens and Arras remained in Allied hands. The newly-won territory would later be difficult to defend against Allied counter-attacks.
The Allies lost nearly 255,000 men. They also lost 1,300 artillery pieces and 200 tanks. All of this could be replaced, either from French and British factories or from American manpower. German troop losses were 239,000 men, many of them specialist shocktroops who were irreplaceable. In terms of morale, the initial German jubilation at the successful opening of the offensive soon turned to disappointment, as it became clear that the attack had not achieved decisive results.