Complex sentence: With this vital piece of evidence in his possession Walsingham had Ballard and the other conspirators arrested and after being tried at Westminster Hall they were all executed in two batches on the 20th and 21st September 1586.
Split into simpler sentences: With this vital piece of evidence in his possession, Walsingham had Ballard and the other conspirators arrested. After being tried at Westminster Hall, they were executed in two batches on the 20th and 21st of September 1586.