The Belgian Government, staking their country’s life upon Hitler’s respect for international law and Belgian neutrality, had not achieved any effective joint planning between their army chiefs and those of the Allies. The anti-tank obstacles and defensive line which were to have been prepared on the front Namur-Louvain were inadequate and unfinished. The Belgian Army, which contained many brave and resolute men, could hardly brace itself for a conflict for fear of offending neutrality. The Belgian front had been, in fact, overrun at many points by the first wave of German assault, even before General Gamelin gave the signal to execute his long-prepared plan. The most that could now be hoped for was success in that very “encounter battle” which the French High Command had declared itself resolved to avoid.

On the outbreak of the war eight months before, the main power of the German Army and Air Force had been concentrated on the invasion and conquest of Poland. Along the whole of the Western Front, from Aix-la-Chapelle to the Swiss frontier, there had stood 42 German divisions without armour. After the French mobilisation, France could deploy the equivalent of 70 divisions opposite to them. For reasons which have been explained, it was not deemed possible to attack the Germans then. Very different was the situation on May 10, 1940. The enemy, profiting by the eight months’ delay and by the destruction of Poland, had armed, equipped, and trained about 155 divisions, of which ten were armoured (“Panzer”). Hitler’s agreement with Stalin had enabled him to reduce the German forces in the East to the smallest proportions. Opposite Russia, according to General Halder, the German Chief of Staff, there was “no more than a light covering force, scarcely fit for collecting customs duties.” Without premonition of their own future, the Soviet Government watched the destruction of that “Second Front” in the West for which they were soon to call so vehemently and to wait in agony so long. Hitler was therefore in a position to deliver his onslaught on France with 126 divisions and the whole of the immense armour weapon of ten Panzer divisions, comprising nearly three thousand armoured vehicles, of which a thousand at least were heavy tanks.

These mighty forces were deployed from the North Sea to Switzerland in the following order:

Army Group B, comprising 28 divisions, under General von Bock, marshalled along the front from the North Sea to Aixla-Chapelle, was to overrun Holland and Belgium, and thereafter advance into France as the German right wing.

Army Group A, of 44 divisions, under General von Rundstedt, constituting the main thrust, was ranged along the front from Aix-la-Chapelle to the Moselle.

Army Group C, of 17 divisions, under General von Leeb, held the Rhine from the Moselle to the Swiss frontier.

The O.K.H. (Supreme Army Command) Reserve consisted of about 47 divisions, of which 20 were in immediate reserve bexhind the various Army Groups, and 27 in general reserve.

Opposite this array, the exact strength and disposition of which was, of course, unknown to us, the First Group of Armies, under General Billotte, consisting of 51 divisions of which 9 were held in G.Q.G. (Grand Quartier Général Reserve), including 9 British divisions, stretched from the end of the Maginot Line near Longwy to the Belgian frontier, and behind the frontiers to the sea in front of Dunkirk. The Second and Third Groups of Armies, under Generals Prételat and Besson, consisting, with the reserves, of 43 divisions, guarded the French frontier from Longwy to Switzerland. In addition the French had the equivalent of 9 divisions occupying the Maginot Line – a total of 103 divisions. If the armies of Belgium and Holland became involved, this number would be increased by 22 Belgian and 10 Dutch divisions. As both these countries were immediately attacked, the grand total of Allied divisions of all qualities nominally available on May 10 was therefore 135, or practically the same number as we now know the enemy possessed. Properly organised and equipped, well trained and led, this force should, according to the standards of the previous war, have had a good chance of bringing the invasion to a stop.

However, the Germans had full freedom to choose the moment, the direction, and the strength of their attack. More than half of the French Army stood on the southern and eastern sectors of France, and the fifty-one French and British divisions of General Billotte’s Army Group No. 1, with whatever Belgian and Dutch aid was forthcoming, had to face the onslaught of upwards of seventy hostile divisions under Bock and Rundstedt between Longwy and the sea. The combination of the almost cannon-proof tank and dive-bomber aircraft, which had proved so successful in Poland on a smaller scale, was again to form the spearhead of the main attack, and a group of five Panzer and three motorised divisions under Kleist, included in Germany Army Group A, was directed through the Ardennes on Sedan and Monthermé.

To meet such modern forms of war the French deployed about 2300 tanks, mostly light. Their armoured formations included some powerful modern types, but more than half their total armoured strength was held in dispersed battalions of light tanks, for co-operation with the infantry. Their six armoured divisions, with which alone they could have countered the massed Panzer assault, were widely distributed over the front, and could not be collected together to operate in coherent action. Britain, the birthplace of the tank, had only just completed the formation and training of her first armoured division (328 tanks), which was still in England.

The German fighter aircraft now concentrated in the West were far superior to the French in numbers and quality. The British Air Force in France comprised the ten fighter squadrons (Hurricanes) which could be spared from vital Home Defence, eight squadrons of Battles, six of Blenheims, and five of Lysanders. Neither the French nor the British air authorities had equipped themselves with dive-bombers, which at this time, as in Poland, became prominent, and were to play an important part in the demoralisation of the French infantry and particularly of their coloured troops.

During the night of 9/10 May, heralded by widespread air attacks against airfields, communications, headquarters, and magazines, all the German forces in the Bock and Rundstedt Army Groups sprang forward towards France across the frontiers of Belgium, Holland, and Luxembourg. Complete tactical surprise was achieved in nearly every case. Out of the darkness came suddenly innumerable parties of well-armed ardent storm troops, often with light artillery, and long before daybreak a hundred and fifty miles of front were aflame.