Complex sentence: In 1874, Maria Alexandrovna married Prince Alfred, Duke of Edinburgh, the second son of Queen Victoria and Prince Albert; she was the first and only Romanov to marry into the British royal family.
Split into simpler sentences: In 1874, Maria Alexandrovna became the wife of Prince Alfred, Duke of Edinburgh, the second son of Queen Victoria and Prince Albert. She was the first and only Romanov to marry into the British royal family.