The Siege of Lowestoft was a brief Parliamentarian operation in March 1643 during the First English Civil War, when Oliver Cromwell suppressed a small Royalist rising that had secured the port of Lowestoft in Suffolk. In what was one of the first major actions of Cromwell's Regiment of Horse, [1] the Eastern Association forces seized arms and took the local gentry prisoner to Cambridge. [2] Unlike much of Suffolk Lowestoft was sympathetic to the royalists partly due to her commercial rivalry with the Parliamentarian Great Yarmouth. [3] It was the only battle in the Civil War within the otherwise solidly Parliamentarian Suffolk. [4] Prisoners taken by Cromwell included the courtiers John Pettus [5] and Thomas Knyvett.