It was intended that the division would remain in the United Kingdom to complete training and preparation, before being deployed to France within twelve months of war breaking out.

However, in April 1940, the division was sent to join the British Expeditionary Force (BEF) in France, leaving behind most of its administration, logistical units, heavy weapons, and artillery.

The division was then given a three-month respite in Africa and the Middle East before it returned to fight in Italy during the campaign to break through the Gothic Line.

To avoid war, the British prime minister Neville Chamberlain met with German chancellor Adolf Hitler in September and brokered the Munich Agreement.

[8][14] In April 1939, 34,500 men, all aged 20, were conscripted into the regular army, initially to be trained for six months before being deployed to the forming second-line units.

[23] The war deployment plan for the TA envisioned its divisions being sent overseas, as equipment became available, to reinforce the British Expeditionary Force (BEF) that had been already dispatched to Europe.

[25] However, there was a need for men to guard strategically important locations, known as vulnerable points, and the division was primarily assigned to this duty until December 1939.

[26][38] The intent was that by August their job would be completed and they could return to the United Kingdom to resume training before being redeployed to France as front-line soldiers.

[40] Historian Tim Lynch commented the deployment also had a political dimension, allowing "British politicians to tell their French counterparts that Britain had supplied three more infantry divisions towards the promised nineteen by the end of the year.

He reluctantly caved to the political pressure to release the divisions, having been assured by General Lord Gort (commander of the BEF) that the troops would not be used as frontline combat formations.

Each of the division's nine battalions were equipped with four 2 inches (51 millimetres) mortars, 18 Bren light machine guns, 10 Boys anti-tank rifles and 12 trucks.

This initiated the Battle of Sedan and threatened to split the Allied armies in two, separating those in Belgium from the rest of the French military along the Franco-German border.

There, the division took command of the 25th Infantry Brigade and other assets assigned by Gort, and were dubbed Polforce (after the town of St Pol where the units were waiting).

These two brigades were assigned to defend the La Bassée Canal between Aire and Carvin, a front of 28 miles (45 kilometres), on the flank of Macforce.

[46] The water obstacles posed the only natural barrier between the advancing German armour forces and the rear of the BEF, and potential catastrophic defeat.

Most notably, they record the 137th Brigade suffering "grievous casualties" when German forces broke through their positions on the La Bassée Canal.

[46] On 1 June, the division faced a major German attack, which involved bitter fighting, artillery barrages and heavy casualties.

In response, the 2/5LR, along with anti-tank guns and artillery pieces from the 139th Brigade, were moved 150 miles (240 km) south to Thala to bolster Allied positions.

The following day, the Germans attacked towards Hunt's Gap where the reinforced 128th Brigade (including the Churchill tank-equipped North Irish Horse) was concentrated.

This was part of a larger effort to intercept Axis forces retreating north, from the south of Tunisia where they were being chased by the British Eighth Army.

Mines and German resistance impeded the advance from the beach, and during the day the 16th Panzer Division launched counterattacks with tanks and self-propelled guns.

By 15 October, it had advanced 4 miles (6.4 km) beyond the river to a series of canals that formed the main defensive position of the 15th Panzergrenadier Division.

[105][106] During the rest of September, the division continued its advance and fought a heavily contested battle to seize a ridge beyond the River Marecchia.

During this counterattack, Captain John Brunt conducted an aggressive defence during two actions and helped retrieve wounded men who had been stranded between the lines.

[115] At the end of August 1944, the majority of German military units in Greece began withdrawing because of the Soviet Union's offensive into Romania and the latter changing sides.

On 18 October, supported by British forces, the Greek government-in-exile returned to Athens; this was part of a larger geopolitical move to install a British-friendly, non-communist government in Greece.

[118] After the re-establishment of the Government of Greece, tensions rose, culminating with the EAM attempting to seize power in December and the British military becoming involved within the second phase of the Greek Civil War.

[121] As fighting increased in Athens, Lieutenant-General Ronald Scobie, commander of British forces in Greece, requested the rest of the 46th Division be dispatched to help restore order.

Most of the division's activities during this period were peaceful, with a notable exception being a skirmish at Corinth, when ELAS members were found attempting to smuggle weapons towards Athens.

[131] The historian and writer Giles MacDonogh wrote the division, along with the 78th, were engaged in "some ugly scenes" once the Cossacks and their families realised what was happening; "Tommies used rifles, bayonets and pickaxe handles to convince them to board the lorries that would take them to the frontier."