The Ottoman Empire opened their offensive with an attack on two fortresses near Kinburn, in southern Ukraine. Russian General Alexander Suvorov held off these two Ottoman sea-borne attacks in September and October 1787, thus securing the Crimea. In Moldavia, Russian troops captured the Ottoman cities of Chocim and Jassy. Ochakov, at the mouth of the Dnieper, fell on 6 December 1788 after a six-month siege by Prince Grigori Potemkin and Suvorov. All civilians in the captured cities were massacred by order of Potemkin.