Shortly after midnight Guderian orders his XIX Panzer Corps to head for Amiens and Abbeville which means they will have reached the Channel and completed the encirclement of the Allied armies in the north. There is no natural obstacle in front of the Germans, just flat plain. Guderian gets on the road with the 1st Panzer Div at 4am. Later in the morning, the 1st Panzer Brigade, now commanded by Lt-Col Hermann Balck, runs into British troops for the first time near Albert. The British fight bravely but are unable to keep the Germans from Albert. By midmorning Balck's tanks are at the gates of Amiens, having traveled 35 miles since dawn.

Alarmed by Lord Gort's telephone call to the War Office the night before, Britain's leaders take two important steps:

1. Without informing the French Admiralty, the British Admiralty make the first arrangements for evacuating the BEF via Dunkirk.
2. Churchill, anxious to know how well-founded Gort's pessimism was, sends Gen Ironside over to see him.

Ironside reaches Gort's Wahagnies HQ at 8:15am. Gort writes in his dispatch:

The Chief of the Imperial General Staff... brought with him instructions from the Cabinet that the B.E.F was to move southwards upon Amiens, attacking all enemy forces encountered, and to take station on the left of the French army. Gort replies he can not do that. The move would bring about the collapse of the tottering Belgian army on his left flank, an area about to be attacked by several panzer divisions. His communication lines and his connection with his supply bases are about to be disrupted. In addition, Ironside is also to inform Gen Billotte and the Belgian Command, making it clear to the latter that their best chance is to move that night between the B.E.F. and the coast.

Similar information was to be given by the War Office to General Georges. During the day, however, it appeared that operations were actually directed by General Weygand who later, on May 23rd, announced in a General Order that he was now Commander-in-Chief in all theatres of war...

I put to him [Ironside] my view that withdrawal to the southwestwards, however desirable in principle, was not in the circumstances practicable.

In the first place, it would involve the disengagement of seven divisions which were at the time in close contact with the enemy on the Escaut and would be immediately followed up... The B.E.F. would be obliged to disengage [these] seven divisions... fighting a rearguard action, at the same time to attack southwestwards and finally to break through enemy forces on the Somme...

Secondly, the administrative situation make it unlikely that sustained offensive operations could be undertaken. Communication with the bases was on the point of being interrupted...

Lastly, though I was not in a position to judge, I had the impression that even if I had decided to attempt this maneuver, neither the French 1st Army nor the Belgians would have been in a position to conform.

Despite these pessimistic views, Gort tells the C.I.G.S. that he can be prepared to launch a counterattack south of Arras with two divisions - the 5th and the 50th. The C.I.G.S. agrees with this action and, accompanied by the C.G.S., leaves for Lens to meet Generals Billotte and Blanchard. He meets Gen Billotte in Lens. The latter approves Lord Gort's plan and states that the French will support the attack with two divisions from Gen René Altmayer's French V Corps. Gort warns Ironside the attack has to approved by Gen Billotte who has not given the BEF any orders for 8 days. Ironside then goes to meet with Billotte and Gen Blanchard, French 1st Army commander. He finds them depressed with no plan or thought of a plan. After hearing the British proposal, Billotte accepts the proposal for and attack next day and promises French support. It can be launched simultaneously, from May 21st onward. Ironside returns to Gort who says the French will not carry through on their promise. Ironside then complains to Gen Weygand that there is no coordination in that area and suggests Billotte be relieved.

Early in the morning, Gen Weygand had driven to the French G.H.Q. at Vincennes where he met with Gen Gamelin. About 8am, without a word to his colleagues, the ex-C-in-C went away forever.

At 9am Gen Sir Harold Franklyn, commander of the 5th Infantry Div arrives at Gort's headquarters. He is informed that he now also commands the 50th Northumbrian Div and British 1st Army Tank Brigade. He is ordered to move to Arras and relieve British and French troops holding the line of the Scarpe River east of town. He is to expand the position and block roads south of Arras thus cutting off German communications from the east. Before he can act, his forces have to be assembled. Following its 90-mile retreat from Belgium, the tank brigade has been reduced to 58 weakly armed Mark Is, which carry only a medium machine gun, and 16 Mark IIs, equipped with 2-pounder (37mm) guns. The assembly point is Vimy, 30 miles away. Movement of the two infantry divisions held up because there is not enough troop-carrying transport assigned to either division. The only troops that would be available for an attack south of Arras the next morning would be from a brigade belonging to the 50th Div. Later in the morning Franklyn drives to Gen René Prioux's command post 6 miles north of Arras. Prioux's corps is now patrolling the Scarpe River just east of Arras. Upon Franklyn's arrival he finds a conference in progress with Gen Blanchard, French 1st Army commander, and Gen Ren;&eacure; Altmayer, commander of the French V Corps, who are soon joined by Gen Billotte commanding officer of the 1st Army Group. Prioux's corps now consists of the reduced 1st Light Mechanized Div from the 7th Army, as well as the 2nd and 3rd Light Mechanized Divs. The French generals tell Franklyn they are planning a counterattack southward toward Bapaume and Cambrai. The ask Franklyn to cooperate by attacking Bapaume the next day. Franklyn replies can only do the limited operation assigned to him by Gort. He asks Prioux to move his cavalry west of Arras in order to watch that flank. Prioux also has trouble assembling his forces because many of the tanks had been dispersed among infantry units whose commanders now refused to return them. Prioux threatens actions against the commanding officers if they are not returned, but it does little good. Only a few weak detachments of the 3rd Light Mechanized Div are available to assist Franklyn in his operation. Franklyn also learns that Altmayer's force will need another day to get ready. Frankly, however, goes ahead with plans for next day's attack. It will be a two-pronged attack by two adjacent columns, each of a battalion of tanks and a battalion of infantry as far as 5 miles to the south and east of Arras. Franklyn is determined to carry out the original orders Gort had given him, a limited advance beyond Arras.

While Franklyn is deploying his tanks and troops around Arras, Rommel's 7th Panzer Div approaches the city from the southeast. The Germans want to seize the high ground around Arras. Rommel plans to advance around the western flank of the city with the SS Motorized Division Totenkopf on his left flank and the 5th Panzer driving east of the town. Instead of being with the lead tanks, Rommel goes back to speed up his infantry. They come under heavy fire half a mile east of Wailly. Rommel personally directs some light flak and anti-tank guns and they succeed in knocking out the lead enemy tanks. Then a second group comes up, knocks out several tanks before the remainder are forced to retreat. These enemy tanks are from the British 1st Tank Brigade under Maj-Gen Sir Giffard Martel supported by remnants of Prioux's cavalry corps and are the spearhead of Gen Franklyn's Frankforce attack.

Meanwhile, at this turning-point of the battle in which every hour is decisive, the tempo of events quickens. The battle for Arras starts at 1:40am. At 6am Rommel reaches Beaurains, two and a half miles south of Arras. He is held up for several hours up by French units that have cut his lines of communication. While this is going on, the panzers of the 8th Panzer Division enter Cambrai and from there push on to Bapaume.

The decisive action of the day,however, takes place with Guderian's armor. By 2pm it is on the outskirts of Abbeville. The town is soon captured and light detachments continue south to Aumale, while the 10th Panzer Division is holding on to the junction of the Avre and the Somme. The panzers are advancing so fast they almost capture an RAF unit on an airfield outside Amiens. The only Allied unit in Amiens is a battalion of the Royal Sussex Regiment, attached to the 12th Territorial Div. They are quickly overrun and by midday a swastika flag over the post office to let the Luftwaffe know that the town is in German hands. The panzers then establish a 4-mile deep bridgehead on the south bank of Somme River in preparation for phase two battle of France which would follow the defeat of the northern Allied armies. Meanwhile the 2nd Panzer Div is in Albert waiting for fuel to be brought up. Guderian orders them to find fuel and push on toward Abbeville. The do manage to find fuel and are soon on their way to Abbeville 45 miles away. By 6pm the 2nd Panzer Div reaches Abbeville surprising a French unit drilling on its parade ground. The panzers then break through positions held by the British 35th Brigade who have no tanks and hardly any artillery. Pushing down from Abbeville, down the Somme River, Lt-Col Spitta's Battalion reaches the Channel at Noyelles by dusk. The news brings surprise then elation to the German high command. There is still concern over the panzers' exposed flanks from Hitler and von Rundstedt. They fear that the panzer divisions can be cut off before the infantry can be brought up to support them. This fear is what ultimately saves British army.

By late afternoon the gap between the French armies in the north and those in action along the Somme has grown to 55 miles. At 8pm more of Guderian's panzers reach the coast at Montreuil-sur-Mer./

The bulk of von Kleist's armor forges on toward Calais and Boulogne, swinging inward on the rear of the French 1st Army and the BEF. 'The object of the German maneuver was now quite plain,' writes de Bardies. 'The breakthrough in the center was to be followed by the envelopment of one wing - the stronger, solider left wing... And it certainly seemed that nothing, there and then, could impede its success.'

The Allied armies have now been truly cut in two, and not only by the panzers but also by infantry and artillery. A mass formation of Germans has interposed themselves between the left flank and the center. All the Allied forces fighting in Belgium and Flanders are caught in a trap. This mortal blow will prompt Lord Gort to execute without delay the operation discussed in Lens by Gens Ironside and Billotte. The attack on the left flank, which has been so dreaded by the German High Command (and which Gen Gamelin had been planning to carry out at the time of his dismissal), had not been launched at the favorable moment. Now it was too late.

'Any anxiety on this score became superfluous,' writes Gen Blumentritt, Gen von Rundstedt's Chief of Staff. 'Nothing serious happened. The French remained on the defensive, confronting the 12th and 16th Armies. The crossing of the Meuse and the Franco-British advance into Belgium was the first miracle of this campaign. The immobility of the French in this sector was a second.'

'The Führer is wild with joy,' Gen Jodl writes in his diary. 'He sees victory and peace within his grasp.'

'Had I had as many motorized troops at my disposal then as I have now,' Hitler was to tell his intimates on October 17th, 1941, 'I could have started the southern offensive immediately and the French campaign would have been over in a fortnight.'

To avoid needless loss, Hitler calls off the projected attack on the Maginot Line by von Leeb's Group of Armies.

The surviving tanks of the French 2nd Armored Division regroups in the vicinity of Champlieu, where orders arrived for it to be reconstituted under the command of Col Perré.