After the battle of Kirk Kilisse the Bulgarian high command decided to wait a few days, a decision which allowed the Ottoman forces to occupy a new defensive position on the Lüleburgaz-Karaağaç-Pınarhisar line. Despite this, the Bulgarian attack by the First and Third Army which together accounted for 107,386 rifleman, 3,115 cavalry, 116 machine guns and 360 artillery pieces defeated the reinforced Ottoman Army consisting of 126,000 riflemen, 3,500 cavalry, 96 machine guns and 342 artillery pieces and reached the Sea of Marmara. In terms of forces engaged it was the largest battle fought in Europe between the end of the Franco-Prussian War and the beginning of the First World War. As a result of it the Ottoman forces were pushed to their final defensive position across the Çatalca Line protecting the peninsula on which Constantinople is located. There they succeeded in stabilizing the front with the help of fresh reinforcements from the Asian provinces. The line had been constructed during the Russo-Turkish War of 1877-8 under the directions of a German engineer in Ottoman service, von Bluhm Pasha, but was considered obsolete by 1912. An epidemic of cholera spread among the Bulgarian soldiers after the Battle of Luleburgas - Bunarhisar.
Question: How many years did the Russo-Turkish War last?
Answer: 1