Complex sentence: On 2 November, Russia declared war on Turkey and the Ottomans closed the Dardanelles, next day the British ambassador left Constantinople and a British naval squadron off the Dardanelles bombarded the outer defensive forts at Kum Kale and Seddulbahir.
Split into simpler sentences: On 2 November, Russia declared war on Turkey, resulting in the closure of the Dardanelles. The following day the British ambassador left Constantinople, while the British naval squadron stationed off the Dardanelles bombarded the outer defensive forts at Kum Kale and Seddulbahir.