While attempting to find a viable land route from the Congo to the Mediterranean via Chad he was taken prisoner by Rabih az-Zubayr and hanged.

He built a fortress at Dikoa, to the south of Lake Chad, and attempted to obtain munitions to modernise his army from the British Royal Niger Company.

[2] The French officer Émile Gentil reached the Chari River from the Congo in 1897, and learned that Rabih az-Zubayr had been responsible for the death of Paul Crampel.

[1] De Béhagle was asked to find an economically viable land route via Chad from the Congo to the Mediterranean Sea.

[4] The battle of Togbao took place on 17 July 1899 on the banks of the Chari about 100 kilometres (62 mi) north of Fort Archambault (Sarh).

[4] De Béhagle's body was recovered in 1901 by troops of colonel Georges Destenave, and buried at Fort Lamy (N'Djamena).

[4] The rue Ferdinand-de-Béhagle was opened in Paris in 1932 in the 12th arrondissement near the Museum of African and Oceanic Arts, and was named after the explorer on 3 February 1936.