Arnaud had chosen to enter in the colonial infantry, and when Charles de Gaulle issued the Appeal of June 18 in 1940 for resistance against the Axis, he was a lieutenant stationed at Faya-Largeau in Chad and attached to the Régiment de Tirailleurs Sénégalais du Tchad (RTST), and on 26 August sided with de Gaulle, like all soldiers of the RTST.
The island's temperate climate and Monte Brasil's micro-climate allows the growth of a rich vegetation and woody plants, including Azores laurel (Laurus azorica), local heather (Erica azorica), Faya (Myrica faya), African boxwood (Myrsine africana) and the common Azorean juniper (Juniperus brevifolia).