Shortly after he learned of the failure of Menshikov's diplomacy toward the end of June 1853, the Tsar sent armies under the commands of Field Marshal Ivan Paskevich and General Mikhail Gorchakov across the Pruth River into the Ottoman-controlled Danubian Principalities of Moldavia and Wallachia. Fewer than half of the 80,000 Russian soldiers who crossed the Pruth in 1853 survived. By far, most of the deaths would result from sickness rather than combat,:118–119 for the Russian army still suffered from medical services that ranged from bad to none.