The Siege of Plevna, or Siege of Pleven, was a major battle of the Russo-Turkish War (1877–78), fought by the joint army of Russia and Romania against the Ottoman Empire. The Ottoman defense held up the main Russian advance southwards into Bulgaria for five months, encouraging other great powers to actively support the Ottoman cause. Eventually, superior Russian and Romanian numbers forced the garrison to capitulate. According to British diplomatic historian A. J. P.