Complex sentence: Schellenberg was supposed to offer them $50 million Swiss francs to go to neutral Switzerland but Winston Churchill dispatched an attorney, who happened to be an old friend of the Duke to convince them to leave Portugal.
Split into simpler sentences: Schellenberg was supposed to offer them $50 million Swiss francs to go to neutral Switzerland. But Winston Churchill dispatched an attorney, who happened to be an old friend of the Duke, to convince them to leave Portugal.