In August 1978, Alexander Achenbach, who said he was the prime minister of Sealand, hired many Dutch and German mercenaries to attack Sealand while Bates and his wife were in Austria. They took the platform and took Bates' son Michael hostage. Michael was able to escape and take back Roughs Tower using weapons stored on the platform. Achenbach was charged with treason. He was held there unless he paid DM 75,000 (more than US$35,000 or £23,000). Germany sent a diplomat from its London embassy to Sealand to negotiate for Achenbach's release. He was released after many weeks of negotiation. Roy Bates claimed that the diplomat's visit meant that Germany had "de facto" recognized Sealand.