1840 treaty between the United States and Miami

Military conflict between the United States of America and Mexico from 1846 to 1848

1840 United States presidential election — 14th quadrennial U.S. presidential election

Indigenous Australian Frontier War

1840 battle between Zulu factions

Battle in February 1840

1840 siege during the Russo-Circassian War

1840 battle between China and Britain

1840 battle fought at this river

1840 treaty leading to the Oriental Crisis

1840 battle between Egypt and the Ottoman Empire