The 1840s (pronounced "eighteen-forties") was a decade of the Gregorian calendar that began on January 1, 1840, and ended on December 31, 1849. The decade was noted in Europe for featuring the largely unsuccessful Revolutions of 1848, also known as the Springtime of Nations. Throughout the continent, bourgeois liberals and working-class radicals engaged in a series of revolts in favor of social reform. In the United Kingdom, this notably manifested itself through the Chartist movement, which sought universal suffrage and parliamentary reform. In France, the February Revolution led to the overthrow of the Orléans dynasty by Louis-Napoleon Bonaparte. In 1848, the publication of the Communist Manifesto by Karl Marx would help lay the groundwork for the global socialist movement. The Mexican–American War led to the redrawing of national boundaries in North America. In the United States, mass migration to the new West Coast occurred following the annexation of California from Mexico, with a Gold Rush beginning at the end of the decade. On its northern border, the United States settled the Oregon boundary dispute with the United Kingdom in 1846, thereby solving a domestic political crisis in the former nation. Politics and wars Pacific Islands In 1842, Tahiti and Tahuata were declared a French protectorate, to allow Catholic missionaries to work undisturbed. The capital of Papeetē was founded in 1843. In 1845, George Tupou I united Tonga into a kingdom, and reigned as Tuʻi Kanokupolu. East Asia China On August 29, 1842, the first of two Opium Wars ended between China and Britain with the Treaty of Nanking. One of the consequences was the cession of modern-day Hong Kong Island to the British. Hong Kong would eventually be returned to China in 1997. Other events: July 3, 1844 – The United States signs the Treaty of Wanghia with the Chinese Government, the first ever diplomatic agreement between China and the United States. Japan The 1840s comprised the end of the Tenpō era (1830–1844), the entirety of the Kōka era (1844–1848), and the beginning of the Kaei era (1848–1854). The decade saw the end of the reign of Emperor Ninko in 1846, who was succeeded by his son, Emperor Kōmei. Southeastern Asia The 1841–1845 Siamese-Vietnamese War in Cambodia was a war between Vietnam (then under the rule of the Nguyen dynasty) and Siam (Thailand) under the House of Chakkri. In the increasingly confrontational rivalry between Vietnam and Siam, the conflict was