Complex sentence: Gibson encouraged and approved the king's excess expenditures, and is thought to be the driving force behind some of them, not the least of which was the $100,000 purchase of a state steamboat for travel to Samoa.
Split into simpler sentences: Gibson encouraged and approved the king's excess expenditures, and is thought to be the driving force behind some of them. Not the least of which was the $100,000 purchase of a state steamboat for travel to Samoa.