Jean Bloch took part in the May 1940 campaign as an intelligence officer in the 2nd Regiment of Carabiniers. After the capitulation of the country, he took part in the operations of the Dunkirk perimeter with the 2nd A.A. Brigade Company R.A.S.C., and then went to the United Kingdom. He was one of the first officers to organise the Belgian Forces there, which took part, from September 1940, in the guarding of coasts and airfields during the Battle of Britain. He was company commander, commander of the Tenby training unit, adjutant-major and intelligence, reconnaissance and liaison officer (1st and 2nd Belgian Battalions, 6th Royal West Rgt., etc.). He took part in the Normandy campaign and the liberation of the country as a reconnaissance and liaison officer with the Piron Brigade and the Guards Armoured Division. He entered Brussels on the evening of 3 September, one of the first to liberate the capital. Taken prisoner at the siege of Bastogne, he escaped from Eichstätt in Bavaria, to finish the campaign with the 14th American Armoured Division. In the aftermath of the war, Jean Bloch had a brilliant career in business and was president of numerous organisations and associations, including the Central Israelite Consistory of Belgium, of which he was Honorary President, and the Centrale d'Oeuvres Sociales Juives (Brussels), of which he was Honorary President.

Honorary Lieutenant-Colonel Baron Jean Bloch was holder of, among others, the C.B.E. and the U.S. Bronze Star, Chevalier de la Légion d'Honneur and Grand Officer of the Order of Leopold II. He was Honorary President of the Union Royale Nationale des Evadés de Guerre and of the Comité d'Action des Forces Belges de Grande-Bretagne et Outre-Mer (Action Committee of the Belgian Forces in Great Britain and Overseas), Honorary President of the Union Royale Nationale des Officiers de Réserve de Belgique (Royal National Union of Belgian Reserve Officers) and former President of the Confédération Interalliée des Officiers de Réserve de l'Alliance Atlantique (Interallied Confederation of Reserve Officers of the Atlantic Alliance).

He was knighted by H.M. the King on 1 July 1991.

The members of the Foundation for Contemporary Memory - Stichting voor de Eigentijdse Herinnering would like to pay tribute to the memory of Baron Jean Bloch for the efforts he made to bring this institution - which for a time bore his name - into being. He was one of its founders. He spared neither his energy nor his help to ensure its viability. He was active in its Board of Directors and its Bureau. Finally, he contributed to enriching its documentation collection through multiple donations and to supporting its research work. Jean Bloch was pursuing a study on 'The Jewish Community in Belgium and the Second World War', of which a first version in both national languages was published in the first issue of the Cahiers de la Mémoire contemporaine - Bijdragen tot de eigentijdse Herinnering.