Complex sentence: One prominent member of the family was Robert Yeamans was a sheriff of Bristol, who was executed in 1643 for plotting to seize a city gate and let in a Royalist army to overwhelm the Parliamentary garrison.
Split into simpler sentences: One prominent member of the family was Robert Yeamans a sheriff of Bristol. In 1643 he plotted to seize a city gate and let in a Royalist army to overwhelm the Parliamentary garrison.