Original: When Hitler committed suicide in April 1945, Seyss-Inquart declared the setting-up of a new German government under Admiral Karl Dönitz, in which he was to act as the new Foreign Minister, replacing Joachim von Ribbentrop, who had long since lost Hitler's favour.
Simplified: When Hitler committed suicide in April 1945, Seyß-Inquart became the Foreign Minister in Admiral Karl Dönitz's new German government.