Was the Boston Tea Party really a protest about high taxes on tea?

No. The law behind the Boston Tea Party actually made legal tea cheaper. The protest movement that culminated on 16 December 1773 was not a dispute about high taxes, because the price of legally imported tea was reduced by the Tea Act of 1773. Before the act, legally imported Bohea sold for about 3 shillings a pound. Afterwards, consignees could sell tea for 2 shillings, just under the smugglers' price of 2 shillings and 1 penny.

The Tea Act was meant to rescue a company. Its principal objective was to reduce the massive amount of tea held by the financially troubled East India Company in its London warehouses. A related goal was to undercut smugglers: approximately 86% of all the tea in America at the time was smuggled Dutch tea.

So why the harbor? Protesters worried about principle and power. The act kept the three pence Townshend duty on tea, and Samuel Adams considered the British tea monopoly "equal to a tax" that raised the same representation issue whether or not a tax was applied to it. Merchants had their own reasons: cheaper legal tea threatened to put smugglers of Dutch tea out of business, and they feared the company's government-created monopoly might be extended to other goods.

On the night of 16 December, men disguised as American Indians boarded the Dartmouth and dumped 340 or 342 chests of tea into the harbor. Parliament answered with the Boston Port Act, which closed Boston Harbor until the dumped tea was paid for.