During the colonial period and the early years of the American republic, New England leaders like James Otis, John Adams, and Samuel Adams joined Patriots in Philadelphia and Virginia to define Republicanism, and lead the colonies to a war for independence against Great Britain. New England was a Federalist stronghold, and strongly opposed the War of 1812. After 1830 it became a Whig party, stronghold as exemplified by Daniel Webster in the Second Party System. At the time of the American Civil War, New England, the mid-Atlantic, and the Midwest, which had long since abolished slavery, united against the Confederate States of America, ending the practice in the United States. Henry David Thoreau, iconic New England writer and philosopher, made the case for civil disobedience and individualism.