Complex sentence: After the robbery, however, Ogilvy returned to Scotland and began selling AGA cooking stoves, thus launching him into a career of marketing, and ultimately building one of the largest and most notable advertising agencies in the world.
Split into simpler sentences: After the robbery, Ogilvy ventured to Scotland and began selling AGA cooking stoves, thus launching him into a career of marketing. Ultimately, Ogilvy built one of the largest and most notable advertising agencies in the world.