 In the Franco-Trarzan War of 1825, the French started to assert control of the mouth of the Senegal river against the rival state of Trarza.In the 1850s, the French under the governor Louis Faidherbe, began to expand their foothold onto the Senegalese mainland, at the expense of the native kingdoms.From 1854, Faidherbe started to establish a series of inland forts up the Senegal River.