Upon his dismissal, the Grand Duke was immediately appointed commander-in-chief and viceroy in the Caucasus (replacing Count Illarion Vorontsov-Dashkov). While the Grand Duke was officially in command, General Yudenich was the driving figure in the Russian Caucasus army, so the Grand Duke focused on the civil administration. Their opponent was the Ottoman Empire. While the Grand Duke was in command, the Russian army sent an expeditionary force through to Persia (now Iran) to link up with British troops. Also in 1916, the Russian army captured the fortress town of Erzerum, the port of Trebizond (now Trabzon) and the town of Erzincan. The Turks responded with an offensive of their own. Fighting around Lake Van swung back and forth, but ultimately proved inconclusive.