the 2nd Battalion Guards Rifles and, towards the end of his life, Colonel-in-Chief of the 5th Kievsky Grenadier Regiment. On his twentieth birthday on 29 April1877, the Grand Duke took the solemn oath of allegiance to the Emperor. An educational tour that had been proposed for him was postponed upon the outbreak of the Russo-Turkish War of 1877–78. Sergei took part in the war with his father and brothers, the Tsarevich Alexander and Grand Dukes Vladimir and Alexei. He spent the greater part of his time serving as Poruchik in the Leib Guard under the Tsarevich in southeast Romania. He was consequently promoted to Colonel. On 12 October, following the battle of Meyk, the Emperor decorated him with the Order of StGeorge, for courage and bravery in action with the enemy, for a reconnaissance expedition at Kara Loma near Koshev. At the end of December 1877, Sergei Alexandrovich returned to Saint Petersburg with his father. Alexander II had started a new family with his mistress and Sergei sided with his neglected mother in the breaking of the family's harmony. Empress Maria died in June 1880, and in March 1881 AlexanderII, who had married his mistress, Princess Catherine Dolgoruki, was assassinated by terrorists. Sergei was then in Italy with his brother Paul and Admiral Arseniev. Three months later, in June 1881, the Grand Duke went to Palestine accompanied by Paul and his cousin Grand Duke Constantine Constantinovich. They visited Jerusalem and the sacred sites. He helped to found the Imperial Orthodox Palestine Society dedicated to the upkeep of Orthodox shrines in the Holy Land and the provision of services to Russian pilgrims. He became its chairman, and his status as patron of the Russian presence in Jerusalem is believed to have given him more pleasure than any of his other duties. From 1882 on, Sergei's military career, which occupied an increasing amount of his time in Saint Petersburg and on maneuvers at Krasnoe Selo, advanced still further. On 15 January 1882, his brother, Alexander III, appointed him Commander of the 1st Battalion Preobrazhensky Life Guard Regiment, the elite regiment founded by Peter the Great, with the rank of Colonel. Seven years later, he was promoted to the rank of Major General. On 26 February 1891, he was made Adjutant General of the H. I. M. Retinue. He became the commanding officer in the village of Preobrazhenskoy. Sergei commanded this regiment until