The previous year, the French legislature had voted the first funds for what would become the Dakar-Niger railway line, a key transportation system to link France's colonies.

With the authorization of his ally, queen Hawa Demba Diallo, Governor Faidherbe ordered a fort built at the Khasso village of Médina.

[3] In April 1857, Umar Tall declared war against the Khasso kingdom, and marched on Médina Fort, their nearest outpost, with an army of 20,000 to 25,000 riflemen.

Realizing the difficulties of attacking the well-equipped French, Umar Tall turned his attention to the neighboring Bambara Empire, soon conquering most of its territory including its capital of Ségou.

However, the French continued to expand their West African presence, conquering Ségou and the Toucouleur Empire less than thirty years after Umar Taal's death.