The power of the defense
The last years of the 19th century witnessed the development of automatic weapons in the form of machine guns. Artillery, too, was revolutionized by the addition of recoil mechanisms, which obviated the need to resight the guns after each round and therefore permitted much more rapid fire. As a result the infantry, no longer able to survive the storm of steel sweeping the open terrain, was forced to seek refuge underground. The ineffectiveness of charging cavalry was proved by the immense losses it took during the Crimean and Franco-German wars: unable to follow foot soldiers into underground shelters, it languished and finally disappeared altogether. The tactical defense, rendered invisible by the substitution of smokeless powder for black powder, became much stronger than the offense. This development, the first signs of which could already be seen in the 1850s, dominated the South African War (1899–1902) and the Russo-Japanese War (1904–05)—although most European commanders refused to look facts in the face until the butchery of World War I. During that war, fronts, manned by armies whose troops numbered in the millions, solidified into continuous trench systems that were sometimes hundreds of miles long. Often there were two and even three lines of trenches protected in front by belts of mines and barbed wire hundreds of yards thick. From the rear they were linked to communication trenches, which led into them and allowed reinforcements to arrive without leaving cover.
To overcome a well-entrenched enemy was something that could be achieved, if at all, only by tremendous concentrations of heavy artillery. Directed by forward observers and from balloons and aircraft overlooking the battlefield, artillery fired high explosive, gas, or—ideally, since the two called for different and even contradictory responses—a combination of both. The number of rounds fired could run into the millions; even so, an astute defender needed neither despair nor expose his troops to the physical and psychological effects of a heavy bombardment landing on their dugouts. Instead, leaving only a thin screen to hold the forward line, he could keep his main forces out of the guns’ range. As in Wellington’s day, the preferred location of such defenses—witness the so-called Hindenburg Line built by the Germans in 1917—was on the reverse slope of a hill or ridge. This denied the enemy observation, complicated his planning, and made it much more difficult for him to register his artillery on target.
In its highest and most developed form, the World War I defensive system consisted of a fortified belt several miles deep. Its main strength was not its continuous trenches but rather its being studded with well-positioned, well-camouflaged strongpoints. So long as the belt held intact, the strongpoints faced forward, bringing fire to bear and acting as observation posts for their own defending artillery. They were, however, also capable of mounting an all-around defense even in the absence of communication with one another and with the rear, thus obstructing the successful attacker as well as delaying and canalizing his progress. Standing ready immediately behind the belt were units (usually the size of regiments, sometimes entire divisions) held in reserve for launching counterattacks. In the German army at any rate, the commanders of such units were often authorized, not to say required, to act on their own initiative without waiting for orders from rear headquarters. The saving of time that was achieved in this way usually permitted local breakthroughs to be quickly repaired, as happened at Cambrai in 1917.
In the face of such defenses, the best-organized attacks were often helpless. Attempts to follow up artillery bombardments by infantry attacking in lines (the method selected by the British at the Somme in 1916) merely led to enormous casualties unequaled in warfare before or since. Later in World War I the Germans, commanded by Erich Ludendorff, developed a new offensive system. The usual daylong and even week-long bombardments were replaced by shorter, more intensive barrages in which gas and high explosive were carefully coordinated and which lasted no more than a few hours. To maintain surprise, no registration rounds were fired, the guns being laid solely by means of mathematical calculation and weather reports. The attacking troops were organized in small, self-contained storming parties. Armed with light machine guns, hand grenades, light mortars, and even some specially designed artillery pieces light enough to be manhandled, they used so-called fire-and-movement tactics. Each subgroup advanced, took cover, and provided the other with covering fire in turn. Like other World War I infantry, the German Sturmtruppe suffered greatly from a lack of mobile radio linking them with their own artillery as well as rear headquarters, but, unlike the rest, they were able to overcome this problem to some extent by operating in a decentralized manner, filtering between enemy strongpoints and bypassing resistance in order to penetrate into the rear.
Regarded from a purely tactical point of view, the German methods were very effective. Having proved their worth at Caporetto in 1917, during the great offensives launched in the spring and early summer of 1918 the Germans repeatedly succeeded in driving through British and French defenses. Ultimately, however, they were brought to a halt by the inability of logistic services to follow up over the devastated terrain. Deprived of even the most elementary supplies, the attacking troops were forced to resort to looting and soon lost their cohesion. Sooner or later the breach they made was sealed by the other side’s reserves, leaving them stranded in the salient they themselves had created and thus exposed to counterattacks on three sides. It should be added, though, that the World War I offense stood a much better chance of succeeding in theatres other than the Western Front, including, in particular, Poland, Russia, and Palestine. In those theatres modern weapons—especially heavy artillery, which could not be brought up over underdeveloped transportation networks—were often less dense on the ground. Hence attacks could succeed, and in some circumstances even cavalry remained effective.
Another offensive weapon destined to have a great future was the tank. The idea of employing armoured vehicles on the battlefield was not new, dating back at least as far as Leonardo da Vinci (before 1500), but they first appeared on the battlefield in 1916 at the Somme. World War I tanks were either “male” or “female”; that is, they were armed either with cannon up to 75 millimetres in calibre or else with machine guns. They could drive through wire and cross trenches (sometimes by dropping fascines into them), crush or neutralize strongpoints, lay smoke screens, and serve as mobile cover for the infantry to follow. During the last two years of the war they were often employed in all these roles, sometimes with success (as at Amiens in August 1918) and sometimes without. Success often depended on numbers: tanks operating individually or in small groups, it was found, did not have sufficient shock effect. Their armour, only 12 to 16 millimetres thick, could be defeated by a determined defender employing field artillery, heavy machine guns, or even special rifles firing heavy ammunition. On the whole, then, early tanks were essentially motorized versions of ancient siege machines. Given their short range, low speed, and general clumsiness, they were suitable for little else.
The armoured offensive
In the decade following World War I, some armies accepted the superiority of the defense as a critical characteristic of modern warfare—a train of thought that caused the Maginot Line to be constructed in France. Elsewhere, there was a lively debate concerning the best way to break through defensive belts. Aside from air power, two principal solutions were put forward. One, which stressed continued development of the light infantry tactics that had achieved partial success in World War I, found particular favour in Germany, where the Reichswehr was prohibited from developing and deploying heavy weapons and where the chief of staff, Hans von Seeckt, built an elite army that would cut through the defense “like a knife through butter.” The other solution, particularly popular in Britain, was armour: improved tanks, operating much like the heavy cavalry of old, were supposed to overcome the defense and restore mobility to the battlefield. There were even visions of armies consisting entirely of tanks.
After 1935 the leading theoreticians reversed their positions. Some of the original proponents of tanks, notably the influential British strategist Basil Liddell Hart, now concluded that the defense had become much the stronger form of war and that armoured offensives would come to grief against a properly organized enemy. In Germany, by contrast, faith in the offensive was never lost, although Adolf Hitler encouraged progressive officers to forsake light infantry and take up tanks—in effect taking the tactical principles pioneered by light infantry in World War I and developing, modifying, and adapting them to armoured warfare. As a result, the Panzerwaffe was an elite force that grew out of the cavalry rather than the infantry, but it retained many elements of the latter’s mode of operations, including an emphasis on interarm cooperation, a decentralized system of command operating within an exceptionally disciplined framework, and a penchant for outflanking and bypassing obstacles rather than confronting them head on.
On a higher level, the Germans saw tanks not as simple siege machines but as fit for playing a strategic role. In World War II, the sequence of the previous war was reversed in that making an initial breach in the enemy’s defenses was usually entrusted to the artillery, infantry, and engineers, supported by dive-bombers when the opportunity offered. Once the breach had been made, tanks, accompanied by motorized and later mechanized infantry, poured through. Relying for reconnaissance on the Wehrmacht’s ubiquitous motorcycles, they fanned out in the enemy’s rear, overran his headquarters, cut his communications, and brought about his collapse by virtue of confusion as much as anything else. To ward off counterattacks against flank and rear, reliance was placed both on the Luftwaffe and on excellent antitank artillery (from 1941 some of the latter was mounted on tracked, self-propelled undercarriages, thus creating what were effectively turretless tanks useful both for tank hunting and for close support). To permit all these various troops to cooperate with one another, the Germans added signal troops (they were the first to develop a comprehensive mobile communication system based on two-way radio) as well as a headquarters. Thus, they created the first armoured divisions, which from 1940 became the very symbol of military might.
Changes in command
As armoured tactics developed, the position of the commander as well as the role he played in battle changed. Primitive and ancient commanders, with the partial exception of Roman ones, normally took an active part in the fighting. They and their medieval successors delivered and received blows themselves as a matter of course, with the result that they were sometimes wounded, as was Alexander the Great, or taken prisoner, as was Francis I of France at Pavia in 1525. However, during the second half of the 16th century bureaucratic means of government began to take over from feudalism, and changing social mores no longer required that rulers fight in person. The switch from hand weapons to firearms itself permitted better control, causing commanders to put more emphasis on directing combat and less on participating in it. Increasingly they were to be found not in the midst of their troops but well to the rear, standing on a hill. After about 1650 they could use a “spying glass,” or telescope, in order to distinguish their units (newly clothed in uniform) from one another and from the enemy. To communicate their intentions to subordinates they would rely on messengers—and indeed it was in this period that the modern aide-de-camp made his appearance.
An important 19th-century development consisted of electric communication in the form of the telegraph and, later, the telephone. Replacing mounted messengers with the infinitely faster wire made it possible to exercise active command even with armies very far apart and, equally significant, with armies distant from headquarters, located far to the rear. As a result, distances between field commanders—to say nothing of commanders in chief—and their troops tended to increase until they could be measured in miles and even tens of miles. Commanders and their staffs left the field for the office, getting their information by reading reports and bending over maps rather than peering between their horses’ ears. After 1860 the old expression coup d’oeil, which implied a commander “casting a glance” over the battlefield and making his decision on the spot, was replaced by “estimate of the situation,” with its connotation of cooler deliberation. The point was reached when, during World War I, commanders from division level up seldom visited the front; nor would the six-foot-deep trenches, screened by concertina in front, have allowed them to take a good look at the enemy even if they had visited it. Moreover, wired communication systems were basically immobile, and efforts to protect them by burying them in the ground tended to make them even more so. In this way they acted as another factor that favoured the defense over the offense.
As commanders came to rely on the wireless communications developed between the world wars, they were able to forsake their headquarters and take to modified tanks, half-tracks, trucks, or even jeeps, which were distinguished from other such vehicles merely by the forest of antennas that they carried. In this way they were able to see the front for themselves and provide leadership at decisive points, all the while keeping in touch with other sectors of the front as well as rear headquarters. In his memoirs, Dwight D. Eisenhower, supreme commander of the Allied forces during World War II, wrote that soldiers usually welcomed his visits because these meant that there was no danger in sight; but other commanders in that conflict, such as Heinz Guderian, Erwin Rommel, George S. Patton, and even Bernard Montgomery (while still merely an army commander) operated in a very different manner from their World War I predecessors. Instead of ensconcing themselves in châteaus, they roamed all over the theatre of war, not seldom taking to the air and covering hundreds of miles in a single day. Regarded from this point of view, radio helped to reverse a secular trend that had been unfolding for centuries, enabling those who knew how to use it to bring about a revolution in command. But for this, modern armoured operations as pioneered in World War II would have been impossible.
