Madeira was an important wine in the history of the United States of America. No wine-quality grapes could be grown among the 13 colonies, so imports were needed, with a great focus on Madeira. One of the major events on the road to revolution in which Madeira played a key role was the seizure of John Hancock's sloop the "Liberty" on 9 May 1768 by British customs officials. Hancock's boat was seized after he had unloaded a cargo of 25 casks (3,150 gallons) of Madeira wine, and a dispute arose over import duties. The seizure of the "Liberty" caused riots to erupt among the people of Boston.