From there he conquered for Castile the islands of Fuerteventura (1405) and El Hierro, ousting their local chieftains (majos and bimbaches, ancient peoples).

In 1390 he accompanied the Duke of Touraine on the Barbary Crusade, an expedition organized by Genoese merchants to address North African piracy.

[4] The French force, consisting of 1,500 knights under the leadership of Louis II, Duke of Bourbon, lay siege to Mahdia in Tunis.

Tired of the oppressive heat and concerned about the upcoming winter, the French agreed to a treaty negotiated by the Genoese.

It is likely that Béthencourt heard stories regarding the Canary Islands from the Genoese, and of the presence of orchil, a lichen used to make a rare and expensive dye.

To finance his expedition he sold his house in Paris valued at 200 gold francs and some other small pieces of property in December 1401.

[5] His cousin,[6] Robert de Bracquemont, French ambassador to Castile, loaned him 7,000 pounds against a mortgage of Bethencourt's estate.

[5] According to Moreri, King Henry III of Castile entrusted the conquest of the Canaries to Braquemont who gave the commission to Béthencourt.

[2] Béthencourt set sail from La Rochelle on 1 May 1402 with eighty men, mostly Gascon and Norman adventurers, including two Franciscan priests (Pierre Bontier and Jean le Verrier[5] who narrated the expedition in Le Canarien), two Guanches who had been captured in an earlier Castilian expedition and were already baptised, and Jean Arriete Prud'homme who would assist in the conquest as a key adviser and administrator.

While Gadifer de la Salle explored the archipelago, Béthencourt left for Cádiz, where he acquired reinforcements at the Castilian court, and was recognized as Lord of the Canary Islands, as a vassal of the King of Castile.

Probably in December 1405, Bethencourt sailed back to France, and entrusted his nephew Mateo or Maciot de Béthencourt with the government.