Complex sentence: Admiral Sir Frederick Beauchamp Seymour was in command of a fleet of about 15 Royal Navy ironclad ships and when a riot broke out in Alexandria and Europeans were killed, the Royal Navy responded, ostensibly to protect the lives and property of British subjects.
Split into simpler sentences: Admiral Sir Frederick Beauchamp Seymour was in command of a fleet of about 15 Royal Navy ironclad ships which sailed to Alexandria when a riot broke out and Europeans were killed. The Royal Navy arrived in the port city to protect the lives and property of British subjects.