It was a tactic approved by international law, so-called 'abordage', by which attackers approach the target ship displaying the flag of a third country on their ship, switch the flag to their own when they come close enough, attach the side of their ship to the target ship, and board to attack.
これは当時万国公法にて認められた戦法、いわゆる「アボルダージュ」であり、至近距離まで第三国の国旗を掲げて接近し至近距離で自国の旗に切り替え、接舷の上、特攻するというものである。