This article aims to study the treaties of peace and trade ratified between Western European States and North African Ottoman provinces. Based on the law of nations, consular correspondence, diaries and gazettes, it describes the concurrence of diplomatic and political European mediators in Algiers during the 1670s, i.e. the Franco-Dutch War and after. This article focuses both on French consul Laurent d'Arvieux and Dutch envoy Thomas Hees. An Arab and Ottoman Turkish speaker, d'Arvieux was sent to Algiers by Colbert to defend French interests (of the so-called «Bastion de France») and to negotiate, with dey Hāj Muhammad and his nephew Bābā Hasan, the maintenance of peace between France and Algiers. The relations between d'Arvieux and Algerian «Powers» turned sour. The article analyzes the several points of disagreement. The stay of d'Arvieux in Algiers is compared with Thomas Hees's journey in Algiers, who managed, with the assistance of a Jewish middleman, Jacob de Paz, to conclude a treaty of peace and trade with the local «Powers». A third European emissary is also scrutinized to understand the stakes of Algerian and Ottoman diplomacy, namely the English consul Samuel Martin, who met both d'Arvieux and Hees. Those French, Dutch and English negotiations in Algiers reveal the crucial importance of North Africa in early modern Mediterranean diplomacy.