Of at least as much interest as any of these projects for many contemporary sources was the so-called Royal Donation whereby royal assets - mostly land and buildings - was transferred from the king to the state, subject to various exceptions and restrictions covering matters such as the inalienability of the assets. This removed the risks arising from royal assets in Belgium from coming into the ownership of the king's three daughters and their foreign husbands. As Justice Minister, Van den Heuvel was closely involved in negotiating and drafting the necessary settlements, which also, in some respects, provided templates for the transfer in 1908 of the distant and inaccessible Congo Free State from the king's personal asset portfolio to the Belgian state as the Belgian Congo. After eight years at the Justice Ministry, van den Heuvel resigned his office in May 1907, which coincided with a change of prime minister (though not of the ruling party). He was a Belgian delegate to the Second International Peace Conference at The Hague between June and October 1907, and thereafter remained an active member of the political establishment. He was nominated a Minister of State in 1908. "Minister of State" in Belgium may be described as an honorary title, but during the years that followed Van den Heuvel was deeply involved in attempts to improve the conditions of the Belgian Congo. A few years later, in 1914, and together with Paul Hymans and Henri Carton de Wiart, Jules Van den Heuvel drafted the Belgian reply to the German Ultimatum which preceded the German invasion of Belgium and so, for Britain and France, military participation in the First World War. Beyond the world of politics, on 8 May 1908 Van de Heuvel was elected a corresponding member of Belgium's Royal Academy, becoming a full member on 5 May 1919. When war broke out in August 1914 he followed the government when it relocated to Antwerp, and then into exile in Normandy. In 1915 the Prime Minister, Charles de Broqueville appointed him as the country's Minister Plenipotentiary to the Holy See, a de facto ambassadorship which he retained till 1918. After war ended Jules Van den Heuvel attended the Paris Peace Conference, at the request of the Foreign Ministry, and drew up the schedule of damages suffered by Belgium. He chaired one of the three sections of the allied Reparations Commission. His contribution was cut short, however, when he suddenly resigned his political duties and from his university teaching on health grounds.