During the 1930s, the British government had planned to deter war by abolishing the Ten Year Rule and rearming from the very low level of readiness of the early 1930s.

Until the early 1930s, the War Office intended to maintain a small, mobile and professional army and a start was made on motorising the cavalry and the artillery.

By 1930, the Royal Army Service Corps (RASC) had been mechanised, some of the artillery could be moved by tractors, and a few engineer, signals and cavalry units had received lorries.

The force and its air support would act as a deterrent greatly disproportionate to its size; plans were made to acquire sufficient equipment and training for the TA to provide a minimum of two extra divisions on the outbreak of war.

It was expected that a British army in Europe would receive continuous reinforcement and in 1936, a TA commitment of twelve divisions was envisaged by Duff Cooper, the Secretary of State for War.

The "continental hypothesis" came fourth and the main role of the army was to protect the empire, which included the anti-aircraft defence of the United Kingdom (with the assistance of the TA).

[6] In February 1938, the CID ruled that planning should be based on "limited liability"; between late 1937 and early 1939, equipment for the five-division field army was reduced to that necessary for colonial warfare in the Far East.

In the first version of the "new conspectus", spending was put at £347,000,000, although in 1938 this was cut to £276,000,000, still substantially more than the deficiency plan for 1936 but much of this sum was for anti-aircraft defence, a new duty imposed on the army.

[11] In February 1939, the first four regular army divisions of the Field Force had been promised to the French, scheduled to reach the assembly area in France on the thirtieth day after mobilisation.

[24] The Second and Ninth armies were dug in on the west bank of the Meuse on ground that was easily defended and behind the Ardennes, giving plenty of warning of a German attack.

[28] In Belgium, German glider troops captured fort Eben-Emael by noon on 11 May; the disaster forced the Belgians to retreat to a line from Antwerp to Louvain on 12 May, far too soon for the French First Army to arrive and dig in.

The British infantry began to arrive on the Dyle on 11 May and dug in screened by light tanks and Bren carriers operating west of the river until 14 May, when the front line units were ready; the bridges were then blown.

A communication breakdown caused a loss of co-ordination with the Belgian Army to the north-west of II Corps and a dangerous gap opened up between the two; fortunately it was covered by British light armour before the Germans could discover and exploit it.

[39] The three Territorial divisions, which had arrived in April equipped only with small arms, intended for construction and labouring tasks, were distributed across the path of the German spearhead.

The three divisions were grouped together in an improvised corps called Petreforce and on 18 and 19 May, the Territorials, lacking motor transport, began to march or entrain towards their defence positions.

Shortly afterwards, infantry assaults started along the whole front, crossing the canalised river either by inflatable boats or by clambering across the wreckage of demolished bridges.

[49] The II Corps commander Lieutenant General Alan Brooke, was ordered to conduct a holding action with the 3rd, 4th, 5th and 50th Infantry Divisions along the Ypres–Comines canal as far as Yser, while the rest of the BEF fell back.

[56] Allied forces north of the Somme were cut off by the German advance on the night of 22/23 May, which isolated the BEF from its supply entrepôts of Cherbourg, Brittany and Nantes.

Only after contacting the Howard-Vyse Military Mission at GQG and receiving a message that the 51st (Highland) Division was retreating with IX Corps towards Le Havre, did Dill learn the truth.

[63] The retreat to the coast began after dark and the last troops slipped away from the Béthune river at 11:00 p.m. Units were ordered to dump non-essential equipment and each gun were reduced to 100 rounds to make room on the RASC transport for the men.

Fortune and Ihler set up at a road junction near Veules-les-Roses to direct troops to their positions and by the morning of 11 June, IX Corps had established a defence round St Valery.

Only at Veules-les-Roses at the east end of the perimeter, were many soldiers rescued, under fire from German artillery, which damaged the destroyers HMS Bulldog, Boadicea and Ambuscade; 2,137 British and 1,184 French troops were evacuated.

[65] Near dawn, the troops at the harbour were ordered back into the town and at 7:30 a.m., Fortune signalled that it might still be possible to escape the next night, then discovered that the local French commander had already surrendered.

A Brigade managed to force its way out but lost the wireless truck for liaison with the 51st (Highland) Division and Stanley-Clarke ordered Arkforce on to Le Havre.

[63] On 9 June, the Admiralty ordered Le Havre to be evacuated and the Commander-in-Chief, Portsmouth sent a flotilla leader, HMS Codrington across the channel, accompanied by six British and two Canadian destroyers, smaller craft and Dutch coasters (known as schuyts).

The troopship SS Bruges was beached and the electric power was cut, rendering the cranes on the docks useless and improvised methods to embark heavy equipment were too slow.

On 12 June, RAF fighters deterred more raids and the quartermaster of the 14th Royal Fusiliers got the transport away over the Seine via the ferry at Caudebec and ships at Quillebeuf at the river mouth.

[71] On 12 June, Weygand had recommended that the French government seek an armistice, which led to an abortive plan to create a defensive zone in Brittany.

The German advance began again during the day, with the 157th Infantry Brigade Group engaged east of Conches-en-Ouche with the Tenth Army, which was ordered back to a line from Verneuil to Argentan and the Dives river, where the British took over an 8 mi (13 km) front.

[79] An intelligence report by the German IV Corps, which had been engaged against the BEF from the Dyle line to the coast, was circulated to the divisions training for Operation Sealion.