1940 May 25th. Seige of Calais.

The Siege of Calais (1940) was a battle for the port and town of Calaisduring the German blitzkrieg which overran northern France in 1940. It immediately preceded Operation Dynamo, the evacuation of the British Expeditionary Force through Dunkirk. It has long been a subject of debate whether the sacrifice of the largely British garrison at Calais contributed to the successful evacuation from Dunkirk.
The German Drive to the Channel

On 10 May 1940, the Germans launched their offensive against France, Belgium and the Netherlands. Within a few days, the concentrated German Panzer Group achieved a breakthrough against the centre of the French front near Sedan, and drove westwards. On 21 May, they captured Abbeville at the mouth of the Somme River, cutting off the Allied troops in Northern France and Belgium from those to the south.The Panzer Group, spearheaded by the XIX Panzer Korps under General Heinz Guderian, turned to its right and drove against the rear of the cut-off Allied armies. Guderian's corps consisted of three Panzer Divisions and an SS motorised infantry regiment. They advanced north along the coast almost unopposed, although they were harassed by air attacks.

Actions on May 23 

The 3rd Royal Tank Regiment (RTR), the 229th Anti-tank battery of the Royal Artillery and the Queen Victoria's Rifles (QVR) arrived in Calais on 22 May. The haste with which the units were moved meant they were not properly ready for action. Four of the anti-tank battery's twelve guns had to be left behind. 3RTR (commanded by Lieutenant Colonel Reginald Keller) was equipped with twenty-one Light Tank Mk VI and twenty-seven Cruiser Mk I tanks. They had no chance to test fire or "zero" their tanks' armament, nor were most of their radios fitted. The QVR were a motorcycle reconnaissance unit of the Territorial Army. Because of a staff officer's error, the motorcycle combinations were left behind, and the personnel arrived in France without transport and equipped only with small arms.The Royal Tank Regiment had orders to advance from Calais to Boulogne, which was under attack. They also were ordered by Lieutenant General Douglas Brownrigg, the Adjutant General of the British Expeditionary Force, to detach some tanks to escort a convoy of trucks carrying rations for the British Expeditionary Force to the east. In the afternoon of 23 May, the main body of the tank regiment advanced south. At Guînes, they encountered half the German 1st Panzer Division (Kampfgruppe Kruger) which was skirting Calais. About half the British tanks were knocked out and the remainder retired to Calais. The German battlegroup continued to drive past Calais, fighting actions against the 1st and 2nd Searchlight Regiments of the Royal Artillery, fighting as infantry, east of the town during the evening.The armoured detachment escorting the ration trucks also became tangled with the German battlegroup during the night. The trucks turned back but some of the tanks pushed on to Gravelines, where they knocked out several German tanks before being overrun the next morning.