World War: Defense in Depth

After the catastrophe on the Somme in 1917, General Ludendorff was persuaded by a group of his junior staff officers to withdraw to a line running north-south behind the Canal du Nord between the Somme and the Scarpe River. By this move he saved his troops from a second Somme and shortened his line. More important, he gained the opportunity to prepare on virgin ground and far away from hostilities for defensive tactics which his bright young men, notably Colonel Fritz von Lossberg, had evolved for divisions after observing the French use for smaller units.

Old Stuff. Until 1917, each side attacked or defended linear fronts. In attack their tendency was to stretch and strain. On defense they tended to crack. Sent to the rear, Colonel Lossberg proceeded to construct a new kind of major fortification, based on zonal defense. He built what the Allies called the Hindenburg Line. It was not Hindenburg’s and it was not a line. The Germans called it the Siegfried Stellung (Siegfried Position).

The tactical principle of the Siegfried Position was that of defense in depth; the idea being that an offensive force may crack a narrow wall but will be stopped or bounced back by a series of cushions and springs backing up each other. Colonel Lossberg’s new type of front was some two miles deep, divided into forward zone, battle zone, rearward battle zone and two more rearward zones for mobile reserves.

Built of wire, wood, earth and some concrete, the Siegfried Position consisted of barbed wire entanglements, behind which came intrenchments and pillboxes connected with secondary intrenchments. Behind these were independent forts and strong points. From these, reserve troops, stationed far enough in the rear to be out of reach of enemy artillery, could be thrust out in any direction in counterattacks when the attacking enemy was exhausted by its advance. At this point the zonal defense system became an ideal means of launching a powerful offensive.

In April 1917, Colonel Lossberg was rewarded with the job of Ludendorff’s Chief of Staff, and even though 18 months later his fortifications had fallen and his cause was lost, he had earned his brassard. When on September 29, 1918 the men of the U. S. II Corps went up against the final defenses of his Siegfried Position at Bellicourt, they had hell’s own time. Between Bellicourt and Bony the St. Quentin Canal passed through a tunnel. In complete safety from shellfire the Germans massed reserve troops who lived in there on barges, ate in kitchens carved from the side of the tunnel and could mount to their hidden outside fighting positions through a maze of upward warrens. No sooner had the Americans seized one mouth of the tunnel than the Germans poured out of their surface positions and riddled them from the rear. The Americans finally cleared the area but not before the 107th Infantry had lost 337 men killed and 658 wounded, the heaviest loss on a single day for any U. S. regiment.

New Stuff. Last week the British and French were again up against a Siegfried Stellung (see p. 28).* Four hundred and fifty miles long, it begins at the point where the Rhine enters The Netherlands, parallels the Dutch, Belgian and Luxembourg frontiers about eight miles behind the Our, Sauer and Moselle Rivers, then skirts the Saar to the French border, then turns west and south along the Rhine and through the Black Forest until it reaches the Swiss frontier at Lake of Constance (see map). It has been under construction for three years and at one time last spring half a million laborers worked on it 20 hours a day. “The world’s cannon and artillery cannot break through it,” boasted the German high command as it was being rushed toward completion this summer. But in principle the new Siegfried Stellung is just a three-ring version of Colonel Lossberg’s old zonal defense system of 1918.*

The Westwall section 100 miles east-west behind the Saar Valley, along which the Allies were feeling for a soft spot, is one of the newest. Behind it valleys run into the Rhine from the North and East. But no military observer expected any immediate smashing of the Siegfried Stellung, 1939 style.

As in 1918, first comes the barbed wire; then huge anti-tank teeth and a “carpet” of mines; then the self-sufficient machine-gun and anti-tank gun emplacements, some firing by remote control. Saar-brikken lies within this defensive zone, six to 18 miles deep packed with hidden anti-aircraft gun pits. Then come the bunkers and major fortifications. The average over-all depth of the Siegfried Position is 30 miles and it embraces 22,000 separate fortified positions (see cuts pp. 30, 31).

Unlike the solid, continuous Maginot Line, the Siegfried Position carries on the old Lossberg concept of defense in depth and swift counterattack from a protected rear. A break-through would be the signal for the great rear fortifications to open up with heavy artillery fire (spare gun-barrels as well as a large supply of munitions are cached in deep caverns connected by tunnel railways). Mobile troops, hitherto protected, would thrust out at the invading flanks. The cushion-&-spring force would be terrific.

How to Take It is a question the French General Staff must have been thinking about a long time. Steady artillery pounding, while useful for protecting advancing troops, probably cannot do the most important part of the job. In an advance, artillery must advance too, and artillery advances are not measured in hours but in days. Furthermore, artillery duels between open and emplaced positions have a way of going in favor of the latter.

Best Allied bet seemed to be the destruction of the vast supply system needed to feed and munition the 1,000,000-odd men the Germans will have within and behind the Siegfried Position. This is the bombers’ job. That done, infantry could then be given a chance to do what skillful infantry has done since time immemorial: take up terrain favorable to it and unfavorable to the enemy—on ridges, slopes, behind spurs—and when the counter-attackers uncoil their spring, let them have it. A bath of dragon’s blood made the hero Siegfried invulnerable except for one spot on his back where a leaf stuck, and that is where Hagen’s spear got him.

*The whole frontier fortification is called Siegfried. Adolf Hitler named the part which faces France the Limes, for Limes Germanicus, the old Roman wall and earthworks that ran along the same position. But Limes Germanicus was built against the Germans, to keep the Teuton barbarians out of the Roman Empire.

*Aged 71, Major General Fritz von Lossberg retired from the Army in 1927.