[8][9][6][10] At the outbreak of war in the summer of 1914, the 1st Battalion the East Surreys were deployed as part of the British Expeditionary Force (BEF) into northern Belgium.

In the trenches at Mons he recounted how he had to hit his men on the backside with his sword in order to gain their attention and remind them to fire low as they had been taught.

[13] His citation reads: For most conspicuous gallantry and devotion to duty on 20 April 1915, when he was commanding a company of his battalion in a front trench on "Hill 60," which was subjected to a most severe bombardment throughout the day.

Towards evening, his company being dangerously weakened, he went back to his battalion headquarters, represented the situation to his commanding officer, and brought up reinforcements, passing backwards and forwards over ground swept by heavy fire.

This young officer was one of the few survivors of his company, and showed a magnificent example of courage, devotion and tenacity, which undoubtedly inspired his men to hold out till the end.

[15][16] In addition to his Victoria Cross, he was awarded the Russian Order of St George (4th Class) and the French Croix de Guerre,[17][3] and was Mentioned in Despatches.

[34] During the inter-war period, Roupell served in Gibraltar, the Regimental Depot, India and the Sudan and he attended the Staff College, Camberley.

[39][40] At the outbreak of the Second World War, in September 1939, Roupell was promoted to colonel and,[41] made an acting brigadier,[42] placed in command of 36th Infantry Brigade from 7 October 1939.

The German thrust near the Somme river towards Abbeville eventually cut off the BEF, northern French and Belgian forces from the rest of France.

[43]When the brigade headquarters was overrun on 20 May 1940, Roupell gave the order for the survivors to split up into small groups and endeavour to re-contact Allied troops.

With the help of the French Resistance they were moved through unoccupied France into non-belligerent Spain, finally boarding ship in Gibraltar and returning to the United Kingdom.