 The increased demand for shipping was the result of several factors.The discovery in 1848 of gold in California was a major cause along with the wars between Great Britain and China in 1840-42 and 1856-60 threw a part of the China trade into American hands.The revolutionary outbreaks of 1848 interrupted European trade, with a resultant benefit to Americans, while the Crimean War, which occupied many European boats in transporting troops and supplies, gave new openings to American ships.