He was born in Harwich, England, the son of William Henry Souper, an army officer on half pay; Philip Dottin Souper was an elder brother.

[2] The family later moved across the English Channel, for financial reasons, establishing themselves in Saint-Omer, and then Ghent.

He was then selected by Minister Rafael Sotomayor, and was present in the Naval Battle of Angamos.

He became a member of the Army General Staff, and participated in the Battle of Pisagua (November 2, 1879) and the Battle of Dolores (November 19, 1879); helping capture the Peruvian province of Tarapacá, which was effectively separated from the rest of the country.

During the Chilean offensive against Tarapacá, he served under General Manuel Baquedano as his Aide de Camp.