In his will, Benjamin Franklin donated 1000 pounds sterling (worth about $272,000 today) to the cities of Boston and Philadelphia. But his gifts came with some strings attached. For the first century, the cities were required to invest 100% of the money. After a century they could spend 75% and let the remaining 25% grow for another century. So did compound interest make the cities fabulously wealthy? Not really. After 200 years, the gifts were worth a relatively modest $6 million combined.
History could have been quite different, had Napoleon pursued writing instead of warmongering