Complex sentence: Under the terms of the Boxer Protocol of 7 September 1901, China had granted nations with legations at Beijing the right to station guards at twelve specific points along the railway connecting Beijing with Tianjin to ensure open communications between the capital and the port.
Split into simpler sentences: Under the terms of the Boxer Protocol of 7 September 1901, China had granted nations with legations in Beijing the right to station guards at twelve specific points along railways connecting Beijing with Tianjin. This was to ensure open communications between the capital and the port.