The earliest histories of British and Irish castles were recorded, albeit in a somewhat fragmented fashion, by John Leland in the 16th century and, by the 19th century, historical analysis of castles had become popular. Victorian historians such as George Clark and John Parker concluded that British castles had been built for the purposes of military defence, but believed that their history was pre-Conquest – concluding that the mottes across the countryside had been built by either the Romans or Celts.