Complex sentence: Keyes was one of the first men to climb over the Peking walls, to break through to the besieged diplomatic legations and to free the legations: for this he was promoted to commander on 9 November 1900.
Split into simpler sentences: Keyes was one of the first men to climb over the Peking walls, to break through to the besieged diplomatic legations and to free the legations. For this he was promoted to commander on 9 November 1900.