The Rise and Fall of the Hindenburg Line

The irreplaceable losses in the "big battles" of 1916 raised awareness of a looming manpower crisis for all the war's original participants. None, however, more deeply felt the urgency of the hour than did Germany, the most capable and driven of the Central Powers. The Kaiser and his allies were now engaged in a desperate war of attrition with a more populous coalition. Trading casualties at the same rate meant—with mathematical certainty—inevitable defeat. In other postings, we have discussed how the German Navy successfully argued for unrestricted U-boat warfare to shift the odds. Germany's army, that is to say Hindenburg and Ludendorff, eventually supported the scheme but were not as confident of its success as were the admirals. They still had to deal with a wearing, multi-front ground war that seemed to be turning against them. Being more experienced on the Eastern Front, they decided their best hope for final victory lay in focusing on knocking Russia out of the war in 1917.

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Hindenburg Line Southwest of Bullecourt
Barbed Wire Belts on Left, Trenches, Tank Traps, Bunkers to the Right

What to do in the west, though? After many pronouncements of "No Retreat!" Ludendorff analyzed the numbers and concluded he did not have a enough divisions to secure the the Western Front as it was configured in late 1916. The line needed to be shortened and strengthened. What grew out of subsequent staff studies was the almost incredible complex of reinforced concrete bunkers, deep zigzagging trenches, massive belts of barbed wire, and anti-tank obstacles known as the "Hindenburg Line." 

The Hindenburg Line  was the strongest defensive system built during the First World War. Its reputation for impregnability was matched only by its ambitious design. Jagging across most of the Western Front in Belgium and northern France, nothing like it had ever been seen before. Requiring an enormous amount of labor and material, its extensive fortifications included deep zigzagging trench lines fortified with reinforced concrete shelters, heavily armed strong points, and wide belts of barbed wire combined to form an intimidating barrier for any attacking army and to maximize the firepower of war's two greatest killers—artillery and machine guns. The fortifications also skillfully integrated natural topographic features such as ravines, villages, and waterways to afford every possible advantage to the defending troops and make any Allied advance as difficult and dangerous as possible. Perhaps its most ingenious use of terrain was creating the world's longest anti-tank ditch from the St. Quentin Canal. 

Reinforced Concrete Bunker Under Construction

In 1917 the system lived up to its promise, as this chronology suggests:

1917

16–20 March: Operation Alberich: the German Army withdraws to the Siegfried-Stellung in anticipation of an Allied spring offensive.

9 April–7 May: During the Battles of Arras and Bullecourt, the German Army's new defensive doctrine is put to the test against the British Expeditionary Force.

16 April–9 May: The German Seventh Army employs the army's new defensive doctrine to defeat a massive French offensive during the Second Battle of the Aisne (Nivelle Offensive).

31 July–10 November: In response to the British offensive during the Third Battle of Ypres, Army Group Crown Prince Rupprecht deepens the defenses of the Flandern-Stellung.

11 November (Ironic date, no?): The German High Command decides to launch a major offensive to defeat the British Army before American forces arrive on the Western Front in strength. 

In the Argonne Sector, American Troops Breaking the Hindenburg Line

To drive the Germans from French soil, the Allies knew they had to overcome these obstacles — and it was a deadly task requiring new weapons and tactics. Ludendorff's decision to renew the offensive in early 1918, however, depleted his forces for the coming crisis when the Americans were present in strength and the Allies were prepared to implement their own improved offensive schemes. The 1918 spring offensives had some success, bringing the German Army within artillery range of Paris, but fresh American divisions arrived on the battlefield, denying victory and sapping German morale. By the time it became necessary for the German Army to fall back to the Siegfried, Wotan, and the other withdrawal positions, it was too weak and demoralized to properly defend them. The Allies, employing new combined arms tactics and weapons, supported by a substantial logistics train, were able to nullify any advantages the fortifications provided to the German Army. Germany's last line of defense proved a forlorn hope.

Source: Over the Top, January 2017