Who was George Grenville, and what did he hope to accomplish in America? Was he successful?

George Grenville was a British Whig politician who served as prime minister from 1763 to 1765. Grenville's tenure as prime minister was brief but disastrous. He did not get along with King George III, who found Grenville tiresome. His decisions to enforce the Sugar and Molasses Act of 1764, also known as the American Revenue Act and the Stamp Act of 1765, were some of the events that led to the American Revolution.
The Sugar Act, as it is usually called, was designed to end the smuggling of molasses and to address tax evasion on imports of sugar and molasses from the French and Dutch West Indies. Grenville reduced the tax on molasses from six pence per gallon to three pence per gallon but strictly enforced it. Protests from the American colonies insisted that the tax should not be any more than one pence, or one penny, per gallon, as that was all the market would tolerate. Grenville refused to listen and instituted the tax. Other items were also taxed, such as sugar, some wines, coffee, and fabrics. The tax on molasses led to the decline of the rum industry in some colonies, which then reduced the number of colonies with which others could trade. Not having as much revenue from trade made some colonies unable to afford manufactured goods from Great Britain.
Distillers in New England benefited from the hole left in the market. However, they did not appreciate the increased interference from the British, who also had the right to seize and confiscate ship cargoes if ship masters did not pay duties or violated a trade rule. The Sugar Act was a scheme to increase revenues for the British Empire and to recoup losses from the French and Indian War.
Whereas the Sugar Act benefited American colonists while still limiting their trade and freedom on the seas, the Stamp Act was a more direct imposition. It placed a tax on "every piece of printed paper they used." This included shipping documents, legal documents, newspapers, other publications, licenses, and playing cards. The revenue was to be used to protect and defend the American frontier near the Appalachian Mountains. Ten thousand troops had been stationed there.
The tax was small but escalated quickly, especially since each piece of paper one used was taxed. What offended colonists was that the act was an attempt to levy taxes on the colonies without going through colonial legislatures. Colonists saw it as the British legislature overstepping its bounds and disallowing autonomous rule. Furthermore, if they could pass this tax with little to no resistance from colonists, other taxes—bigger taxes—could be imposed in the future.
It seems that Grenville's hope was to establish order in the colonies. He wanted to ensure that colonists paid their taxes on goods. He enforced taxation not only to ensure order, but also to pay for the crown's wars and to secure colonial borders. Though he was decisive, he lacked talent as a politician. He failed to listen to people's concerns and failed to maintain good relationships with people, including the king. Grenville was already out of office by the time the first grumblings of revolution swept the American colonies, but his tax policies had initiated those grumblings.
https://www.britannica.com/event/Sugar-Act

https://www.history.org/history/teaching/tchcrsta.cfm

https://www.ushistory.org/declaration/related/sugaract.html