Complex sentence: The German-Spanish Society, founded in 1918, was concerned with the public relations to Spain and since the Nazi take-over of 1933 was increasingly incorporated into the Nazi propaganda apparatus, and used to propagate the New Order ideology.
Split into simpler sentences: The German-Spanish Society, founded in 1918, was concerned with the public relations to Spain. Since the Nazi take-over of 1933, the society was increasingly incorporated into the Nazi propaganda apparatus, and used to propagate the New Order ideology.