Final answer:
The mystery that was solved following Napoleon Bonaparte's invasion of Egypt was the decipherment of ancient Egyptian hieroglyphs using the Rosetta Stone.
Step-by-step explanation:
The linguistic/literary mystery that was solved following Napoleon Bonaparte's invasion of Egypt was the decipherment of ancient Egyptian hieroglyphs. The discovery of the Rosetta Stone by soldiers in Napoleon's army in 1799 provided the key to unlocking the language of ancient Egypt. English physicist Thomas Young and French scholar Jean-François Champollion were instrumental in deciphering the hieroglyphs and laying the foundations of our knowledge of ancient Egyptian language and culture.