He inherited part of his father's farm at the age of 15. Like his forbears Samuel Gregg II was a devout Quaker. During the American Revolution he was enrolled in the militia but could not serve for religious reasons. He is still considered a patriot because, by Delaware law, he contributed financially to the cause. The Battle of Brandywine was fought very close to his home in 1777. During the War of 1812, soldiers camped on his land to guard a gunpowder works. He became a prosperous farmer. Samuel was known to have been wealthy for the times, and was noted for raising livestock, including fine horses. At the time Deleware was a slave state, but Samuel Gregg freed his last two remaining slaves, a mother and son before he died. He, and his wife who died a year after him, were buried at the Centre Meeting House near his farm.