[2] During the Franco-Mexican War (1864–67), Wahis volunteered for service in the Belgian Legion sent to Mexico to fight alongside French and Imperial Mexican Forces.

His success in the role led to rapid promotion and, in 1892, he was designated the state's next Governor General, replacing Camille Janssen.

[2] Wahis' military background had a strong influence on governance in the Free State and contributed to its increasingly harsh policies of rule.

[2] After Belgium was forced by international pressure to annex the Free State in 1908, Wahis continued as Governor-General of the new Belgian Congo.

[2] Retiring from colonial administration, Baron Wahis became a businessman with a position in a company in the Dutch East Indies and in the Congo's Compagnie du Katanga.