Shortly after taking the throne, Ranavalona annulled the Anglo-Merina treaty that had been concluded between Radama and British envoys, and refused to continue receiving annual payments from Britain in exchange for adherence to the stipulations of the treaty. The most significant of these conditions was the kingdom's non-participation in the international slave trade, which had historically been a major source of revenue for the kingdoms of Imerina, Betsimisaraka, Sakalava and others across the island. One consequence of the termination of the Anglo-Merina friendship treaty was an end to the delivery of modern weaponry, which rendered the queen vulnerable to designs against her from foreign powers and pockets of local resistance. This vulnerability was underscored in 1829 when a fleet of six French ships launched an unprovoked attack against the fort of Foulpointe and the nearby town of Ivondro on the eastern coast of Madagascar. The queen's army successfully repelled the French at the next port, forcing the ships to Île Sainte-Marie, where they engaged a diplomatic envoy sent from Antananarivo by Ranavalona. The protracted negotiations ensured the French suffered from the malaria prevalent in coastal areas, until the increasing casualties forced the ships' withdrawal from Ranavalona's territory.