Mehmed Pasha had little success against Russia, and the first encounter between the Ottoman Empire and her future northern rival presaged the disaster to come. A plan had been devised at Constantinople for connecting the Volga and Don by a canal, and in the summer of 1569 a large force of janissaries and cavalry was sent to lay siege to Astrakhan and begin the canal works, while an Ottoman fleet besieged Azov. However, a sortie of the garrison of Astrakhan drove back the besiegers. A Russian army of 15,000 men attacked and scattered the workmen and the Tatar force sent for their protection, and the Ottoman fleet was destroyed by a storm. Early in 1570 the ambassadors of Ivan the Terrible concluded at Constantinople a treaty which restored friendly relations between the Sultan and the Tsar.