In 1916 he was transferred to the 1st aviation group in Dijon, and in August 1917 graduated as a military pilot from the Avord school and was assigned to the 231 squadron.

[1] Blocq-Mascart returned to Paris and studied at the Ecole libre des sciences politiques.

[1] The OCM was a group of anti-Vichy officers and professionals, particularly strong in Paris and the northern industrial regions.

[5] Arthuys led the movement and was assisted by Roger Souchère as Chief of Staff, Jean Mayer in charge of the first and third Bureaus, Touny for the 2nd Bureau, and Blocq-Mascart for Civil matters.

The group also published Cahiers that discussed the post-war economy and politics, which gave it the reputation of being elitist and technocratic.

He supported giving the OCM a political program and assisted with a project for constitutional and administrative reform that recommended a presidential system.

In it he traced the historical roots of antisemitism and its development in prewar in France, taking a position that could be taken as justification for the view.

[8] He concluded that members of national minorities or non-Christian background should be banned from various occupations and places of residence unless they could prove they had been assimilated for several generations.

[4] Although some Resistance leaders denounced the article, it reflected the views of most French people at the time.

[8] In April–May 1942 Blocq-Mascart joined the Centurie network that Gilbert Renault ("Colonel Remy") had formed with the OCM.

[9] After the Liberation Blocq-Mascart played important roles on the juries of honor and the committees of recognition of the Resistance.

[10] He was president of the National Federation of support centers for internees and political prisoners, then of Entr'aide française (French Mutual Assistance).

[4] Blocq-Mascart supported eugenics as a way to address the low birth rate in post-war France, which he blamed on the casual view being taken of town hall marriages.

[12] After 1951 Blocq-Mascart represented the interests of France in its African colonies as a Conseller d'Etat during the transition to independence.