The German surprise attack through the Ardennes and the crossing of the Meuse at Sedan, forced the First Army to retreat from Gembloux, then back over the French frontier towards Lille.

Leading elements of the French army trained to respond to the armoured and air threat, including those under General Henri Aymes commanding the IV Corps which fought at Gembloux.

French doctrine provided for air reconnaissance and observation, fighter defence of ground forces and on occasion bomber support in principle, although they might not always be available in practice.

[16] The German strategy (Fall Gelb) required the 6th Army (General Walter von Reichenau) to push its mechanised and motorised formations into the Belgian plain and strike at Gembloux, defeating or tying down Allied forces, while the main German effort was made through the Ardennes to the Meuse River (Battle of Sedan), to cut off the Allied forces in Belgium and northern France.

[20] An important consideration in the Allied plan was the assurance that the Belgian army would prepare defences in the Gembloux Gap in the centre of the Dyle position.

As the German invasion was repeatedly postponed, the Belgian command revised the trace eastwards in the hope of "dragging" the French closer to the German-Belgian frontier and on 10 May there was only a partial anti-tank obstacle east of the Dyle line.

Like the French command, the Wehrmacht planned a joint air-land battle, but unlike the Allied air forces, the Luftwaffe had the operational strength, techniques and training to make the idea work.

The French North African and Moroccan units were an elite force in the peacetime army, serving overseas, better paid and attracting the most experienced officers from the service schools.

Enjoying the "absolute confidence" of his men in a unit complete in personnel and armed to the highest standards of the French army of the time, the 15th DIM was ready to contribute significantly to the defence at Gembloux.

By that evening, de La Laurencie's III Corps and units of the British and the Belgian Army on the Dyle position and at Namur made contact with German patrols.

Meanwhile, serious fighting was reported with tanks (of the 3d DLM) in the Walhain and St. Paul areas and French tanks also appeared at Ernage, leading the Panzer Brigade command to conclude that the situation was critical; enemy armour, against which only the 75 mm gun of the Panzer IV was really effective, was trying to break through both on the left and the right with artillery support directed by spotter aircraft while the German infantry had not yet arrived.

[30] Hoepner had decided to throw his tanks with available artillery and air support at a solid French defence rather than wait another day to bring up his two infantry divisions for a more powerful effort.

[31] 6th Army intelligence continued to insist that the Allies were retreating, ordering XVI Corps to pursue and claiming that German tanks were already west of Gembloux (which was false).

Nonetheless, at 22:45 the corps ordered an assault by 3rd and 4th Panzer Divisions for 08:00 of 15 May with the railroad line on both sides of Tilly, well beyond the French defences at Gembloux, as the first objective.

[31] Stever of 4th Panzer Division ordered his 4th Rifle Brigade to deploy three battalions in line from Gembloux to Ernage, echeloned back on their left flank.

At 08:10, riflemen fired white starshell indicating that they had crossed the railroad line, but at 08:20 French artillery engaged the incursion and as the German tanks drove forward, they were pinned down.

The corps operations officer of French descent, Chales de Beaulieu, criticised the 3rd Panzer Division for allowing its infantry to bog down while leaving its tanks in reserve.

By 11:18, the weight of French shelling on approach routes and installations drove the corps artillery commander to conclude that holding gains made and bringing in reinforcements were "gravely threatened".

Captain Jungenfeld was not far from them and noted that as they reached the railroad line all the heavy vehicles of Fourth Company were destroyed, the tank of Oberstleutnant Eberbach, commander of the regiment, was knocked out.

"[33] When the tanks finally began to fall back, the I. Battalion of the 12th Rifle Regiment also withdrew, contrary to orders, forcing staff officers to turn out to stem the retreat.

He decided to reestablish contact with the 1st DIM on the stop-line near Cortil-Noirmont, then to reconquer the main position using the corps reserve (3rd Battalion of the 7th Moroccan Regiment) and La Font's tank brigade.

During the previous night, the batteries of 75s posted forward in the antitank role returned to their battalions, possibly on the assumption that the tank threat was now less pressing than that of the enemy infantry.

Pointed at the Bois de Buis, as likely cover for German tanks, the 105 mm guns fired at maximum rate, provoking heavy air attack from the Ju 87 units.

That of Lieutenant Jouval in the south of the village was encircled by infiltrators by 06:00, the second to the north was outflanked by tanks of the 3rd Panzer Division and infantry and hit by effective artillery fire.

There were solid reasons for delay; the corps artillery commander noted German difficulties in locating and neutralising French batteries and added that logistics units could not make good the heavy consumption of ammunition because of the state of the road net.

[39] Eventually, several German medium tanks crossed the anti-tank obstacle before a large factory which their artillery had shelled and under cover of their fire, the infantry started to advance.

Despite intense French resistance from Chastre, where German sources reported a few Hotchkiss tanks (which, if they existed, could only have come from the 3d DLM), the infantry succeeded in reaching two hills west of Noirmont, the original objective of 3rd Panzer Division on 14 May, pulling forward with them elements of II Battalion which had been holding the line.

General Albert Mellier originally intended to counterattack on his left with tanks of the La Font brigade and 3rd Battalion of the 7th Moroccans Regiment.

At about 14:00, the reserve reestablished contact with a company of the 110th Infantry at Villeroux, but the situation remained critical and the headquarters of the 7th Moroccan Regiment and its supporting artillery battalion began to retreat toward St. Gery.

But it took the Wehrmacht another two weeks of fighting to encircle and capture part of First Army, allowing the rest and the bulk of the BEF to escape to DunkirkFollowing the battle, the 3rd Panzer Division had suffered 20-25 percent of its AFVs knocked out.