In 1826, with the weakening of the Ottoman Empire by the Treaty of Akkerman , he joined the fight for the Greek War of Independence . Following this campaign, he became secretary to the Governor-General of India, before resigning his post to go to Palestine, to Jericho. While staying in Jerusalem, he was made a Knight of the Holy Sepulchre for saving the Temple from being looted. April 1827 He went to Egypt where, some time after his arrival, he entered the service of Pasha Muhammad Ali as a civil engineer and hydrographer. He received an Arabic name, Edris-Effendi, got used to wearing official clothes and became familiar with the Egyptian dialect and local customs and traditions.

Towards the end of May 1835, he fought, as his father had in 1831, against the epidemics that were spreading in Egypt. In turn, he contracted dysentery and was unable to resume his duties until the beginning of the following September. In January 1836, the year the Saint-Simonians returned to France, weary of the demands of the Governor of the Infantry School in Damietta, he submitted his resignation and, finally free, undertook the study of hieroglyphs, in which he became an expert, on par with Champollion. He began to travel through Turkey, Persia, Palestine, Arabia, Lower and Upper Egypt, Nubia, Ethiopia, Abyssinia, Syria, etc., where he spent seventeen years, living off the proceeds of his drawings, his pen, or his family’s resources