In January 1799, during the canal expedition, the French learned of the hostile Ottoman movements and that Jezzar had seized the desert fort of El-Arish 16 km (10 mi) from Syria's frontier with Egypt, which he was in charge of guarding. Certain that war with the Ottoman sultan was imminent and that he would be unable to defend against the Ottoman army, Bonaparte decided that his best defence would be to attack them first in Syria, where a victory would give him more time to prepare against the Ottoman forces on Rhodes. The siege of Jaffa was a military engagement between the French army under Napoleon Bonaparte and Ottoman forces under Ahmed al-Jazzar. On the 3 of March, 1799, the French laid siege to the city of Jaffa, which was under Ottoman control. It was fought from 3 to 7 March 1799. On the 7 March, French forces managed to capture the city. Meanwhile, a plague epidemic caused by poor hygiene in the French headquarters in Ramla decimated the local population and the French army alike. As he had also suggested during the siege of Acre, on the eve of the retreat from Syria-Palestine Napoleon suggested to his army doctors (led by Desgenettes), that the seriously ill troops who could not be evacuated should be given a fatal dose of laudanum, but they forced him to give up the idea.