Complex sentence: After watching a medicine show proprietor stage an elaborate presentation for his wares and noting that people fought to buy the products sold, Gates decided to have a similar production to demonstrate the merits of barbed wire.
Split into simpler sentences: After watching a medicine show proprietor stage an elaborate presentation for his wares and noting that people fought to buy the products sold, Gates had an idea. He decided to have a similar production to demonstrate the merits of barbed wire.