A letter written by His Highness the Prince Elector of Brandenbourgh, : unto his most Serene and Illustrious Highnes Richard Lord Protector of the Common-wealth of England, Scotland, and Ireland ... Denoting Their Highness's joynt-interest in the protecting and defending of the Reformed Protestant cause; and the Swedes converting of those forces, and means which they receive from England, and their other allyes, for the propagating of the Protestant cause: towards the compassing of their own ambitious ends, the subverting of the Protestant churches, and the disturbing of the publike peace in all parts.