The Invasion of Europe

WE ARE attacking Germany by blockade and by assault. These are the only ways to attack a country, just as they are the only ways to attack a fortress. They are complementary, and usually necessary to each other. Blockade strikes at the enemy's means of making war, seeking to weaken or disarm him. Assault strikes at his armed forces, seeking to overcome them and penetrate into his home territory.

Before the invention of the airplane, blockade could be said to be external pressure, while assault sought to exercise internal pressure. This distinction no longer stands, for air power has made it possible to carry on an internal blockade as well as an external one. The operations of air power are, indeed, a form of blockade rather than a form of assault, curious as this may sound. These operations are directed at industrial facilities, railways, docks, shipping, canal locks, and other fixed targets of like nature. Their purpose is to prevent the enemy from moving raw materials from their sources to manufacturing centers, and from moving finished munitions from manufacturing centers to the fighting fronts. It makes no difference, in principle, whether this process is interrupted by destroying a railway bridge between the mine and the factory, or by destroying the factory itself. The basic idea is to disarm the enemy by depriving him of the means of making things to fight with.

Whether air power by itself can be decisive in the war against such a nation as Germany has been a matter of much controversy. It is a controversy that may never be decided. If the Germans were to offer to surrender unconditionally tomorrow, there would be enthusiasts to claim that air power did it, and there would be counter-enthusiasts to claim that the Russian Army did it. The fact is, of course, that if there were no Russian Army, the Germans would be able to put a lot more effort into defending themselves against Anglo-American air attack; and if there were no air attacks they would be able to do much more against the Russian Army. You can carry this a little farther and point out that if there were no British and American navies, there would be no effective air attacks. The vast bulk of material which makes them possible could not be ferried across the Atlantic Ocean because of the U-boats; nor would the Russian Army be as tough a customer as it is, for a great deal of its best equipment -- particularly the motor transport which is the core of its 1943 offensive -- comes by sea from the arsenals of North America and Britain. Total war cannot be carried on effectively by one means alone. It demands the coördinated use of all methods of striking at the enemy. Teamwork, not any one fighting arm, is the key to victory.

For the moment, Britain and the United States are doing most of the blockading, and the Russians most of the assaulting. But unquestionably, the Allied High Command has decided upon a full-scale invasion of the European Continent by Anglo-American forces. The Germans face not only intensified air attacks but also the prospect of having to fight on two major land fronts, at the same time keeping in check the civil populations of their territories. What measures will they take to defend themselves?

II

The area which the Germans must defend is considerably less than the area which they now occupy. As long as they can hang on to the Lorraine iron mines, the coal and iron of Polish Silesia, the Rumanian and Galician oil fields and the mineral deposits of Jugoslavia, these, with their imports of Swedish iron, their own native resources, and their accumulated reserves, will enable them to carry on a long defensive war.

Germany's western industrial district in the Ruhr valley has been the principal target of our air power and has suffered severely; so also have other western industrial centers. The Germans have tried to counter this loss by transferring industries to safer areas and by building up the existing industries in other parts of the territory they control, notably in Czechoslovakia, Austria and Silesia. They have decentralized their industry as much as possible, especially their aircraft plants. There is, of course, a limit to what can be done in these directions. The production of steel, for example, is not an economical process except in close proximity to large coal fields. The bulk of the coal used in producing a given amount of steel is so great that long hauls from mine to foundry are not efficient. The Germans are not worried about production costs as far as balance-sheet figures are concerned, but they must take into account the terrific strain now being put on their railways and canals. They are short of locomotives, freight cars and barges. Their transportation system is one of our major air targets, and it is likewise suffering from all the ills which beset the German industrial plant as a whole. The moving of German industries from the places where the natural laws of economics originally caused them to be established, to other sites dictated by strategic necessity, imposes unnatural strains on this harried transportation system.

The effect of the continued air attacks must be to force the Germans to abandon occupied territory. This is a logical method of providing better air protection for the essential industrial districts. As the fighting fronts are contracted, less mobile field artillery is needed, for example, and hence more antiaircraft guns can be turned out. And all the equipment for repelling bombers can be concentrated. The Germans will retreat according to plan -- if they can. They will do it in such a way as to gain the greatest possible advantage from it, and to leave behind them the fullest measure of chaos; but withdrawals are inevitable.

From the strategic point of view, the Germans must first of all take into account the geography of Europe. The most important topographical feature of the Continent is the great mountain wall of the Alps (extended eastward by the Carpathians), which stretches right across the middle of Europe from the Gulf of Lions to the western end of the Black Sea. North of this wall lies the European coastal plain, which begins at the Pyrenees, includes most of France, all of Belgium and Holland, and almost all of Germany and Poland, sweeping on to the east to lose itself in the vastness of the Russian steppes. The would-be invader of Germany must fight his way into the central portion of that plain in order to reach Germany's vital centers. He must, therefore, have a foothold in France or the Low Countries on the west, or in Poland on the east, or he must storm the passes of the mountain wall on the south.

At this writing, the Anglo-American forces have no foothold in France or the Low Countries. To get one, or to invade Germany from the German coast or through Denmark, they must effect a landing against a defense that will certainly be more powerful, more concentrated and better coördinated than the opposition to our landings in North Africa and Sicily. The German defensive measures in the west will make such a landing a very costly operation. No beachhead can be established against strong coastal defense except under the most complete air cover. That primary consideration restricts the likelihood of a landing in western Europe, based on Great Britain, to that part of the coast of Holland, Belgium and France which lies within 100 to 125 miles of British air fields, this being the practical limit for fighter radius of action. Roughly speaking, then, a large scale invasion of that western shore must take place somewhere between the mouth of the Scheldt and the mouth of the Seine. This stretch of coast is, of course, the scene of the strongest German counter-preparations, and it also happens to be that coastal area where the German communications are best and shortest, so that they can bring to bear the most powerful opposition.

The chance of a landing in Brittany, or on the Atlantic coast of France, should not be ruled out, however. Such an invasion would have to be supported by long-range aviation plus carrier-based aviation. It would be possible as a diversion for a more important attack; or it might be a main effort if the Germans were already very busy elsewhere.

With the Allies in possession of Sardinia and Corsica, a landing on the Mediterranean shore of France will also be feasible, for there is a stretch of the Côte d'Or 80 miles long which on the average is only about 115 miles from the northern coast of Corsica. Such a landing would be still easier if it were part of a larger operation which included an assault from Italy against the Alpine passes separating Italy and France. But that would mean that the Allies were in possession of the plain of Lombardy and the valley of the Po, which the Germans may decide to hold in strength. It is an attractive plan, for it imposes heavy burdens on the German communications and is a combination of two methods of assault -- the breaching of the mountain wall and the landing from the sea.

No landing is necessary at the eastern end of the north European coastal plain. The Russian armies are already advancing across their steppes toward the plains of Poland. There are no natural obstacles in their path save the great rivers of the region and the Pripet marshes. The Russians are superior in numbers to the Germans, though probably not yet superior in equipment, or in what may be called -- for lack of a better term -- tactical resourcefulness. The Germans here must base their defense on exploiting their superior skill and equipment by the use of every artificial obstacle and fortification which their engineers can devise. But the insufficiency of manpower both behind the lines and for fighting must compel the Germans to seek ever shorter fronts. The geography of the region favors such a plan. As the Germans retire westward from their present positions, the length of the Russian front contracts steadily; and they can even count on the front being divided, for defensive purposes, into two separate short fronts when they have reached the region of the Pripet marshes.

The European southern, or mountain, front is divided into three parts. The first is the Alpine front between France and Italy. Next, after the interval formed by neutral Switzerland, comes the mountain wall which divides Italy from Austria and northwestern Jugoslavia. Finally there is the Balkan front, which presents a series of mountain barriers beginning clear down at the head of the Aegean Sea and stretching back to the final barrier of the Carpathians. The Germans must decide where and how these several fronts will be defended.

Under modern conditions of warfare it is better to begin the defense of a mountain barrier by defending the approaches to the passes. If no such position is held and the enemy is able to move directly upon the passes, a mountain chain is not as formidable a barrier to military movement as it used to be. The Germans themselves proved this in their Balkan campaign and in Norway. If the attacker has good mountain troops he will quite surely be able to get hold of one or more passes, once he is beyond the approaches. The only hope of preventing him from passing over is a counterattack by strong reserves when he is (in the military term) astride the pass. But the attacker will always have air superiority; he would not be the attacker if he did not. And that air superiority can interfere drastically with the efforts of the defense to bring its reserves into action. In forcing a mountain pass, a powerful air cover acts as in forcing a beachhead, giving the attacking troops protection from counterattack until they are firmly established.

In other words, mountain warfare has now become as much a warfare of manœuvre as fighting in open country, although of course it is slower manœuvre and carried out by smaller units. The German Staff will not look upon mountains as impregnable defenses. Their chief value to a defender is that they impose delay and restrict the number and capacity of the enemy's lines of communication. An army which has passed through a mountainous region, and whose communications with its base remain dependent on the roads and railways of that region, is limited in size by the precariousness and awkwardness of the supply lines.

The geography of the southern front makes it seem desirable for the Germans to try to hold northern Italy as long as they can, in order to protect the approaches to the French and Austrian passes. Southern and central Italy are strategic liabilities, and for the most part economic liabilities as well, if the Germans have laid up sufficient reserves of sulphur, lead and zinc. The line of the Etruscan Apennines, roughly from Leghorn to Ancona, offers one possible defense position; the line of the river Po offers a second; and a third, that of the Piave, is available for defense of the approaches to the Brenner Pass and the Austrian frontier. But the loss of southern Italy is disadvantageous to the Germans in that it offers the Allies a base of operations against the Balkan peninsula.

The Balkan front is a difficult one for the Germans. Probably their most hopeful course is to fight desperately to prevent an Allied lodgment there at all. The Allies now have no foothold in the Balkans. To get an army there, they will have to come in from the sea, and to do that they will have to begin by reducing the island outposts which command the approaches to the Aegean Sea. That in turn is the avenue to Saloniki -- the gateway of the Vardar-Morava valley -- the only practicable approach to the heart of the Balkan peninsula which an invading Allied army can use. The reduction of Crete, with its strong fortifications and its picked German garrison, may prove even more troublesome than the reduction of Sicily, especially as the Allied bases are not as close to Crete as Tunisia, Malta and Pantelleria were to the Italian island. An approach by way of Cyprus to Castelorizzo to Rhodes seems probable. Indeed, Rhodes is in many ways the key to the Aegean, and the chink in the Cretan armor.

Once the outposts are driven in, so to speak, the German situation in the Balkan peninsula becomes more difficult at each step. From southern Italy, and the Aegean Islands, if they can be taken, the Allies can immediately do two things: they can start sending supplies and reinforcements across the Adriatic Sea to the Dalmatian ports of Jugoslavia, and they can start transforming the Aegean Islands into air bases and supply depots for a landing at Saloniki. It is hardly practicable to send an army of invasion across the Adriatic Sea from Italy; the seaports of Jugoslavia are small and their communications with the interior run through the terrific passes of the Dinaric Alps. But there are many brave, tough fighting men already in those mountains who ask only weapons and direction to launch themselves against the Germans. If they can be induced to stop fighting each other, and are supplied with light automatic arms, grenades, explosives, portable radios, light mortars and small fast tanks, as well as reinforcements in the shape of engineers, signal troops and specially trained units of mountain artillery, they can give the Germans a great deal of trouble. With proper air assistance, they might be able to cut the Belgrade-Nish-Saloniki railway and keep it cut. If this were done, the Germans would have difficulty in making a defense at and around Saloniki. And it certainly would take a great many German troops to keep that railway guarded.

With the Serbs in arms, and with Saloniki taken, the Germans must eventually withdraw to the line of the Danube and the Sava; and they must stand on that line. If they fail to make that stand good they permanently lose the Rumanian oil fields, one-half their supply. They risk the turning of the line of the Dniester, and a junction between the Allied right and the Russian left somewhere on the Moldavian plain. When these things happen, Germany is in a bad way.

III

There are two other factors in the defensive strategy of Germany. One is the question of defense against air attack. Germany must not only build up physical defenses; she must keep Allied air bases at a distance. On the east, the Russians -- whose strong point has never been strategical bombing -- can be allowed to come quite a bit nearer than they are now without undue German risk, though the industrial district of Silesia must be protected at all costs. On the south, however, the Germans cannot allow the establishment of Allied air bases in the plain of Lombardy if they are to keep inviolate their Czech and Austrian industrial regions, which hitherto, like Silesia, have gone comparatively untouched. The Germans will probably turn almost the whole attention of their aircraft industry to the production of fighters. A very considerable increase in the scale of antiaircraft protection for key industrial centers seems also certain; it will result naturally from a withdrawal in the occupied territory, as we have noted.

The remaining factor to be considered is naval strategy. There is evidence that the U-boat is being effectively dealt with. Should the Germans be compelled to abandon the U-boat campaign, the effect on their strategy would be a diminished interest in the Atlantic ports of Norway and France. As for the German surface fleet, it seems possible that some of its heavy units may be deliberately sacrificed in a desperate attack on the Atlantic shipping which is bringing to Europe the power that turns the balance against Germany. The remainder will be required to protect the left flank of the German Army, on the Baltic Sea, as the retirement from Russia develops.

To summarize. The object of German strategy from this time on must be to gain time -- time for the United Nations to sicken of the bloodshed, time for dissensions to arise among them, time for political shifts of power in Germany herself which may make it possible for her to secure better terms. The German "Heartland," without which Germany cannot go on fighting, may be described as the territory of Germany itself, western and central Poland, Denmark, the Low Countries, Czechoslovakia, Hungary, Rumania, northern Jugoslavia, Austria, Luxembourg, Belgium, the Netherlands and part of northern France. This central and vital area must be held. Once it is invaded, the beginning of the end is at hand, and the end itself not too far away.

It is, of course, a much smaller area than the Germans now possess. In Russia, they may find themselves compelled to give up much of their present conquests and they may do this rather suddenly, in a strategic withdrawal in great depth and on a broad front. They may also have to abandon Finland and southern and central Italy. But the rest -- Norway, western and southern France, the Aegean Islands, the southern Balkans, northern Italy and western Russia -- may be the scene of furious delaying actions, in which the German object will be to exact heavy Allied losses without paying too great a price themselves. They will try to keep their positions well consolidated and linked up. They will form powerful reserve armies from the forces they save by their Russian withdrawal. They are unlikely again to take the risk of pushing out large forces into exposed positions, as they did at Stalingrad and in Tunisia. And they will have to abandon hope of an offensive in the air in order to purchase increased defensive power. They may also have to abandon their offensive at sea.

The defeat of Germany will come about when the German Heartland can no longer be defended.