During the campaign of may 1940 and the following month, King Leopold III had as principal political counsellor Henri De Man. He played a primordial role during that period, which was rich with extremely important events for the future of Belgium, such as the surrender of the army and the problem of the King reassuming or not his constitutionalprerogative during the occupation. The former socialist minister did not accidentally hold the situation of confident of the King. Indeed, both men became friends before the war. They shared similar conceptions about interior and foreign policyproblems. In fact, Leopold III supported De Man in his attempt, during the winter 1938-1939, to convoke a peace conference. On the other end early 1939 they both expressed rather similar conceptions on the functioning of the Belgian institutions and especially on the lack of authority of the executive power. The projects of manifestoes by De Man concerning the political future of Belgium were grounded on a reinforcement of the executive power. So the manifesto of june 1940, a consequence of De Man's contacts with the King, reveals the role which the King should or could have assumed if Hitler had permitted it.