After the French had fully committed the best of the Allied armies to Belgium between 10 and 12 May, the Germans enacted the second phase of their operation, a break-through, or sickle cut, through the Ardennes, and advanced toward the English Channel.

The German official history stated that in the 18 days of bitter fighting, the Belgian Army were tough opponents, and spoke of the "extraordinary bravery" of its soldiers.

Militarily it would put the Allied rear at right angles to the French frontier defences; while for the British, with their communications located at the channel ports, would be parallel to their front.

Despite the risk of committing forces to central Belgium and an advance to the Scheldt or Dyle lines, which would be vulnerable to an outflanking move, Maurice Gamelin, the French commander, approved the plan and it remained the Allied strategy at the outbreak of war.

A significant mobile reserve was needed to guard the rear areas, and as a result it was considered that the protection against a sudden assault by German forces was not sufficient.

[17] King Leopold III made a speech on 14 October 1936 before the Council of Ministers to persuade the people and their government that Belgium's defences needed strengthening.

The French 2nd Army was responsible for the last 100 kilometres (62 mi) of front, covering Sedan, the lower Meuse, the Belgian–Luxembourg border and the northern flank of the Maginot line.

[30] It was first suggested that a conventional parachute drop be made by airborne forces to seize and destroy the forts' guns before the land units approached.

The offensive, carried out by 125 volunteers of the 34th Infantry Division under the command of Wenner Hedderich, achieved their missions by flying to their objectives using Fieseler Fi 156 Störche.

The objectives of this operation was to land two companies of the 3rd battalion Grossdeutschland Infantry Regiment by Fi 156 aircraft at Nives and Witry in the south of the country, in order to clear a path for the 1st and 2nd Panzer divisions which were advancing through the Belgian–Luxembourg Ardennes.

The Belgians had withdrawn laterally upon the initial invasion and had demolished and blocked routes of advance, which held up the French 2nd Army units moving north toward Namur and Huy.

The delay that the Belgian Ardennes Light Infantry, considered to be an elite formation, could have inflicted upon the advancing German armour was proved by the fight for Bodange, where the 1st Panzer Division was held up for a total of eight hours.

Eight CR.42s were evacuated from Brustem to Grimbergen near Brussels but seven Gladiators and the last remaining Hurricanes from 2/I/2 Escadrille were destroyed at Beauvechain Air Base and Le Culot by He 111s and I./JG 27 respectively.

[74] The French 7th Army, on the northern flank of the Belgian line, protected the Bruges–Ghent–Ostend axis and, covering the Channel ports, had advanced into Belgium and into the Netherlands with speed.

But German parachute forces had seized the Moerdijk bridge on the Hollands Diep river, south of Rotterdam, making it impossible for the French to link up with the Dutch Army.

[83] In light of the withdrawal to the main defensive line, which was now being supported by the British and French armies, King Leopold issued the following proclamation to improve morale after the defeats at the Albert Canal: Soldiers The Belgian Army, brutally assailed by an unparalleled surprise attack, grappling with forces that are better equipped and have the advantage of a formidable air force, has for three days carried out difficult operations, the success of which is of the utmost importance to the general conduct of the battle and to the result of war.

These operations require from all of us – officers and men – exceptional efforts, sustained day and night, despite a moral tension tested to its limits by the sight of the devastation wrought by a pitiless invader.

The Allied chiefs of staff had sought to avoid an encounter mobile battle without any strong fixed defences to fall back on and hoped Belgian resistance would last long enough for a defensive line to be established.

One account speaks of a German Panzer commander attempting to climb on a Hotchkiss H-35 with a hammer, presumably to smash the machine's periscopes, but falling off and being crushed by the tank's tracks.

[100] The French 1st Army had also taken a battering and despite winning several tactical defensive victories it was forced to retreat on 15 May owing to developments elsewhere, leaving its tanks on the battlefield, while the Germans were free to recover theirs.

[106] Between 16 and 17 May, the British and French withdrew behind the Willebroek Canal, as the volume of Allied forces in Belgium fell and moved toward the German armoured thrust from the Ardennes.

[109] The British cabinet decided that even if the "Somme offensive" was carried out successfully, some units may still need to be evacuated, and ordered Admiral Ramsay to assemble a large number of vessels.

[116] These formations were then largely holding the eastern front as the BEF and French forces withdrew to the west to protect Dunkirk, which was vulnerable to German assault on 22 May.

Without consulting the French or asking permission from his government, Gort immediately and decisively ordered the British 5th and 50th infantry divisions to plug the gap and abandon any offensive operations further south.

[121][122] On the afternoon of 24 May, Bock had thrown four divisions, of Reichenau's 6th Army, against the Belgian IV Corps position at the Kortrijk area of the Leie during the Battle of the Lys (1940).

[125] The Belgian High Command made at least five appeals for the British to attack the vulnerable left flank of the German divisions between the Scheldt and the Leie to avert disaster.

To the west, the German Army Group A had reached Dunkirk and were 4 miles (6.4 km) from its centre on the morning of 27 May, bringing the port within artillery range.

Further to the west the BEF had been forced back, north of Lille just over the French border and was now in danger of allowing a gap to develop between themselves and the Belgian southern flank on the Ypres–Lille axis.

With the exception of a few RAF sorties, the air was exclusively under the control of the Luftwaffe, and the Belgians reported attacks against all targets considered an objective, with resulting casualties.

[3] Churchill sent a message to Keyes the same day, and made clear what he thought of the request: Belgian Embassy here assumes from King's decision to remain that he regards the war as lost and contemplates [a] separate peace.