Complex sentence: She returned to Perth briefly in 1919 after her husband was killed on the Western Front in 1918, but was back in Germany in 1920 when she married her husband's cousin, Baur Bamgarten.
Split into simpler sentences: She returned to Perth briefly in 1919 after her husband was killed on the Western Front in 1918. In 1920, she was back in Germany, where she married her husband's cousin, Baur Bamgarten.