Complex sentence: The bitter cold and terrible roads contributed greatly to the annihilation of Enver Pasha's 3rd Army in the previous year; but the Russian General Yudenich viewed this as an opportunity to take the Ottomans by surprise.
Split into simpler sentences: The bitter cold and terrible roads contributed greatly to the annihilation of Enver Pasha's 3rd Army in the previous year. The Russian General Yudenich viewed this as an opportunity to take the Ottomans by surprise.