Jacques was educated at Wrekin College, Shropshire between 1921 and 1925 becoming Head of House in his final year. He was the most highly decorated Old Wrekinian of the Second World War to be killed.

He was Welsh born with dual French/British nationality, and was therefore required to undertake French national service which he did with the French Cuirassiers in the 1930’s.

After leaving Oxford University he worked in the advertising industry in London and Paris and in 1938 married Beryl Richardson.

Described by Professor MRD Foot, with whom he worked during the war, as a "charmer...keenly interested in French politics, brave, adroit, and energetic".

Jacques was called up for war service with the French Army upon the declaration of war on 3rd September 1939 and returned to Orléans.

The following month he was appointed liaison officer to the British II Corps in France on the staff of the C-in-C, General Viscount Gort VC, escaping via Dunkirk in May 1940.

He was secretly returned on 12th June, via Cherbourg, with orders to assist others in their escape efforts.

When France surrendered on 22nd June 1940 Jacques travelled south to Marseille, through to Spain via the Pyrenees, where he was arrested by the Spanish authorities and held in an internment camp until his release was secured by the British government.

Travelling by sea he eventually returned to Britain, landing at Glasgow in March 1941. In April 1941 Jacques was granted a ‘special’ commission in the British Army within the General Service Corps and was recruited by Major Lewis Gielgud [brother of the actor Sir John Gielgud] to join the Special Operations Executive [SOE] as part of the French Section, headed by Maurice Buckmaster.

The recruitment process also saw him being interviewed personally by the Prime Minister, Winston Churchill. His main duties at this time were to pass on his experience in occupied France onto F Section’s wireless operators and saboteurs being sent to France.

On 6th August 1941 he himself was parachuted into Vichy France, together with his radio operator.

SOE staff members were normally precluded from being sent on clandestine missions in case they were captured and interrogated by the SS as they were deemed to know too much about the organisation & personnel of the SOE. In this case, due to the urgency and requirements of his trip, an exception was made.

The objectives of the mission included the recruitment of additional agents, contacting existing agents already in situ, acquisition of paper specimens of ration cards, travel documents etc, for forging back in England. 

Once matters had been concluded a signal was sent back to England, shortly after which he was collected by an RAF Lysander of the Special Duties Flight and flown back to RAF Tangmere.

Success of the mission saw the posthumous award of the MBE promulgated on 9th August 1945, to be dated 9th March 1942.

By 1942 Jacques, in the rank of Major, was inserted into Algeria to head up the French section of the SOE in November of that year.

The following year he landed in Corsica and distinguished himself by his heroism in operations against the Germans.

Following their surrender and withdrawal Jacques returned to London in October 1943 after which he was awarded the Croix-de-Guerre with palms, and the same high award a second time early in 1944 for his invaluable work in assisting with the planned invasion of France on D-Day.

Jacques was again parachuted into France in July 1944 as leader of an Allied mission in the south-western area of the country establishing relations with the local French Resistance and his leadership and organising ability contributed to the successes achieved by the French Forces of the Interior [FFI].

He organised a number of resupply drops by the RAF, deliberately exposing himself to danger of death on numerous occasions in order for success.

Jaques was often engaged in firefights with the Germans and he played a courageous and distinguished part in the fighting in Égletons in mid-August where the German garrison had withdrawn into a concrete building that they had turned into a fortress.

Negotiations for surrender failed and the attacking FFI force was subjected to intensive bombing and machine-gun attacks. Whilst this siege was underway Jacques set off for Ussel, approximately 30km north-west, on roads sprawling with the enemy, carrying fresh supplies of grenades, Bren guns and ammunition to help the local Resistance who had surrounded another German garrison.

On his arrival in Ussel the fighting had more or less concluded so he returned to Égletons where that siege had been abandoned owing to the arrival of German reinforcements.

Determined that the enemy should not succeed, and to ensure their eviction from the area, he arranged for the RAF to attack the strengthened garrison with a squadron of RAF de Havilland DH.98 Mosquito fighter-bombers resulting in a German retreat. Jacques then co-ordinated the continual harassment of the enemy as they retreated inflicting many casualties.

Following the liberation of France, Jacques was seconded to the Special Allied Airborne Reconnaissance Force [SAARF] to help coordinate the rescue of any captured agents, making sure they were not subjected to any vengeance attacks, as well as providing essential information on the conditions of POWs and concentration camps; his mandate taking him across Europe searching for vital information.

Whilst in Germany on one such mission he was involved in a serious car accident near Flossenbürg concentration camp on 16th May 1945.

He was immediately flown to Paris for an operation, and a while later repatriated to a hospital in Burtonwood, Staffordshire, but was to lose his life after further unsuccessful operations on 7th August 1945 at the age of 38.

He was finally returned to his widow in Cardiff for burial where he now lies in the shade of a tree in a quiet corner of Cathays Cemetery.

After his death his SOE superior wrote of him “he was already in the hard early days of the Resistance in the occupied countries, an outstanding figure. He rendered service that few could emulate and none exceed.”

Husband of Beryl Vaillant de Guelis: son of Raoul Vaillant de Guelis & Marie Vaillant de Guelis of Cardiff, South Wales.

London: 21st February 1946: “For his courageous leadership, outstanding organising ability and devotion to duty” the King has been graciously pleased to approve the award of the Military Cross in recognition of gallant and distinguished service in the field. This related to his action in the battle at Égletons.

Paris: 4th October 1947: the Croix-de-Guerre with silver star “Has completed numerous missions in France and Italy. Parachuted 9th July in Corréze and wounded during the Tilleul Mission. On the 17th and 18th August has taken active part in the Egletons battle (Corréze)”.

Drafted by Colonel Rivier, Commandant la 5e Région French Forces of the Interior. Signed by Captain Guery, Chef de la Section Chancellerie du Cabinet de l'Etat-Major de la Defense Nationale. Both awards were conferred posthumously.