He took part in the last four months of the First World War, where he was wounded in the neck and received the first of his citations which included the Croix de Guerre.

[1]: 168 At the outbreak of the war, Valluy was a Major and operations officer with the XX1 Corps, captured by the Germans he was released in 1941 and by 1944 had become a brigadier general in the First Army.

[1]: 156  On 22 November, Valluy ordered the local commander, Colonel Pierre-Louis Debès, to take complete control of Haiphong "and force the Vietnamese government and army into submission.

French aircraft bombed and strafed while the cruiser Suffren, in the harbor, shelled the city, demolishing whole neighborhoods of flimsy structures.

[1]: 170 On 7 October 1947, after months of preparations, Valluy launched Operation Léa with the aim of capturing the Vietminh leadership and destroying their forces in the Viet Bac.

[1]: 201–3 On 20 November, Valluy launched Operation Ceinture between Thái Nguyên and Tuyên Quang, and the French seized Viet Minh supplies and bases.

With limited manpower, he was unable to launch large-scale attacks against the Viet Minh, and 1948 saw him consolidate the gains of the previous year, including the thin string of forts along Route Coloniale 4 (RC4), a circuitous road through ravines and over mountain passes between the towns of Lạng Sơn and Cao Bằng.