Born into a family from Morlaix, Gustave's grandfather was a Deputy from Finistère, and his father was a military engineer trained at the prestigious Ecole Polytechnique.

Between 1880 and 1883 Borgnis-Desbordes was Commandant-Superieur du Haut-Fleuve, Commander of the Military Territory of Haut Senegal, which was later expanded to the east and rechristened French Soudan in 1890.

In the process he launched a series of military campaigns against the remnants of the regional power of the Tukulor Empire, which was finally overthrown by Colonel Louis Archinard in 1890.

Under both Brière de l'Isle in Senegal, and as chief officer in the Soudan, Borgnis-Desbordes developed a reputation for violence and insubordination, leading the territorial expansion of French power in the absence of, and sometimes in direct contradiction of the Ministry of Marine, the government arm which controlled colonial forces.

Borgnis-Desbordes led the French conquest of the remnants of the Imamate of Futa Toro, along what is today the northeastern border of Senegal, which Briere de l'Isle ordered in contradiction of government directives.

Blocked by the colonial minister in Paris, Briere de l'Isle argued that Kaarta was a threat to the new protectorate in Fouta Tooro, and that British agents were infiltrating the area.

The Ministry gave in, and on 7 July 1878, Borgnis-Desbordes forces destroyed the Kaarta Toucouleur fort at Sabouciré, killing their leader, Almany Niamody.

From his base in Kita, Borgnis-Desbordes had the authority to conduct all aspects of French policy in the Soudan, including exploration, railway construction and defense.

With a battalion of Tirailleurs sénégalais at his command, Borgnis-Desbordes set about the work of establishing bases all along the proposed Dakar-Niger Railway, bringing African states under French rule, and scouting for a rail terminus on the Niger River.

In fact, Cloué had given strict orders that no movement to the east would take place as fellow Marine officer Joseph Gallieni was then in Segu, negotiating a trade treaty with the Toukolor leaders, and under virtual house arrest.

In fact, he became their expert on the Soudan, (Gallieni was now in Martinique recovering from his long stay in Segu) and Borgnis-Desbordes briefings carried much weight.

Colonel sent a column that reached the Niger, crossed the river, and attacked forces of Samory Toure that were besieging a local leader at Kiniéran.

[5] In early March 1882, the French government approved funding for the railway (even at 7,500,000 francs, a doubling of previous requests), and placed Jauréguiberry, a former Governor of Senegal and supporter of expansion, as Minister of Marine.

[6] Borgnis-Desbordes attacked the Toukolor fortress at Murgala in December 1882, risking the reignition of war with the major empire of the central Niger valley.