<P> In World War II, the Japanese attacked Pearl Harbor on December 7, 1941 . Germany and Italy, led respectively by Adolf Hitler and Benito Mussolini, declared war on the United States, and the U.S. Congress responded in kind . </P> <Table> <Tr> <Th> War </Th> <Th> Declaration </Th> <Th> Opponent (s) </Th> <Th> Date of declaration </Th> <Th_colspan="2"> Votes </Th> <Th> President </Th> <Th> Result </Th> </Tr> <Tr> <Th> Senate </Th> <Th> House </Th> </Tr> <Tr> <Td> War of 1812 </Td> <Td> Declaration of War upon the U.K. </Td> <Td> United Kingdom </Td> <Td> June 18, 1812 </Td> <Td> 19--13 </Td> <Td> 79--49 </Td> <Td> James Madison </Td> <Td> Treaty of Ghent (December 24, 1814) </Td> </Tr> <Tr> <Td> Mexican--American War </Td> <Td> "An Act providing for the Prosecution of the existing War between the United States and the Republic of Mexico ." </Td> <Td> Mexico <P> Mexico </P> </Td> <Td> May 13, 1846 </Td> <Td> 40--2 </Td> <Td> 173--14 </Td> <Td> James K. Polk </Td> <Td> Treaty of Guadalupe Hidalgo (February 2, 1848) </Td> </Tr> <Tr> <Td> Spanish--American War </Td> <Td> Declaration of War upon Spain </Td> <Td> Spain </Td> <Td> April 25, 1898 </Td> <Td> 42--35 </Td> <Td> 310--6 </Td> <Td> William McKinley </Td> <Td> Treaty of Paris (December 10, 1898) </Td> </Tr> <Tr> <Td> World War I </Td> <Td> Declaration of War upon Germany </Td> <Td> Germany </Td> <Td> April 6, 1917 </Td> <Td> 82--6 </Td> <Td> 373--50 </Td> <Td> Woodrow Wilson </Td> <Td> Treaty of Berlin (August 25, 1921) </Td> </Tr> <Tr> <Td> Declaration of War upon Austria - Hungary </Td> <Td> Austria - Hungary </Td> <Td> December 7, 1917 </Td> <Td> 74--0 </Td> <Td> 365--1 </Td> <Td> 1921 U.S.--Austrian Peace Treaty (August 24, 1921), 1921 U.S. - Hungarian Peace Treaty (August 29, 1921) </Td> </Tr> <Tr> <Td> World War II </Td> <Td> Declaration of War upon Japan </Td> <Td> Japan </Td> <Td> December 8, 1941 </Td> <Td> 82--0 </Td> <Td> 388--1 </Td> <Td> Franklin D. Roosevelt </Td> <Td> V-J Day, Japanese Instrument of Surrender (September 2, 1945), Treaty of San Francisco (September 8, 1951) </Td> </Tr> <Tr> <Td> Declaration of War upon Germany </Td> <Td> Germany </Td> <Td> December 11, 1941 </Td> <Td> 88--0 </Td> <Td> 393--0 </Td> <Td> V-E Day, German Instrument of Surrender (May 8, 1945), Treaty on the Final Settlement with Respect to Germany (September 12, 1990), Treaty of Vienna with Austria (May 15, 1955) </Td> </Tr> <Tr> <Td> Declaration of War upon Italy </Td> <Td> Italy </Td> <Td> 90--0 </Td> <Td> 399--0 </Td> <Td> Paris Peace Treaty (February 10, 1947) </Td> </Tr> <Tr> <Td> Declaration of War upon Bulgaria </Td> <Td> Bulgaria </Td> <Td> June 5, 1942 </Td> <Td> 73--0 </Td> <Td> 357--0 </Td> </Tr> <Tr> <Td> Declaration of War upon Hungary </Td> <Td> Hungary </Td> <Td> 360--0 </Td> </Tr> <Tr> <Td> Declaration of War upon Romania </Td> <Td> Romania </Td> <Td> 361--0 </Td> </Tr> </Table> <Tr> <Th> War </Th> <Th> Declaration </Th> <Th> Opponent (s) </Th> <Th> Date of declaration </Th> <Th_colspan="2"> Votes </Th> <Th> President </Th> <Th> Result </Th> </Tr> <Tr> <Th> Senate </Th> <Th> House </Th> </Tr>

When was the vietnam war declared a war