In 1709 the French appeared for the first time in the Red Sea, and carried out a treaty with the governor of Mokha, on behalf of the then Imam El-Mehdi. The principal clauses referred to religious toleration, the duties on merchandise, and that redress should be given for any insults offered to French subjects.[21] In spite of this treaty in 1738 Mokha was bombarded by the French, on account of debts owing to the traders by the governor of that city. The town was taken, but handed back to the Imam on the payment of the debt. This ended in the drawing up of a second treaty, somewhat reducing the duty chargeable on the imports and exports. For the next twenty years affairs in the Yemen remained in a state of tolerable peace. From time to time tribes raised the standard of independence; but there seems to have been no organised attack upon the Imams, although the family was continually engaged in intrigue as to the succession. However, in 1758 a serious rebellion broke out, under a certain Abd er-Rabi ibn Ahmed, who had been governor of a small province in the service of the Imam. Abd er-Rabi had made enemies in the household of the Imam, and at their instigation was recalled. He refused, however, to obey, whereupon the Imam sent a force of some three thousand men to bring him. Nevertheless, he was able to hold out within the walls of Kátaba for no less a period than nearly a year, and eventually made his escape by night to his followers in the tribe of Hajeriya. Finding it impossible to capture Abd er-Rabi, the Imam made overtures to the Sultan of Aden to assist him. Abd er-Rabi hearing of this, entered Lahej and blockaded Aden. He was destined, however, to fall a victim to an act of treachery. The Imam was at this period attacking the city of Taiz, which he was unable to capture, and, hoping to kill two birds with one stone, invited Abd er-Rabi to join him. This the latter did, and the city was taken. The Imam, delighted with his success, under the most solemn protestations of friendship invited him to Sanaa, where on his arrival he was, after every ignominy had been showered upon him, decapitated.[22] [Illustration: HOWTA, THE CAPITAL OF LAHEJ.]