Era
20th century
38
1900-1999
16
1939-1945
14
1933-1945
7
1861-1865
6
Civil War, 1861-1865
6
17th century
5
21st century
5
To 1500
5
1889-1945
4
1968-1998
4
1990-
4
19th century
4
Since 1900
4
1767-1838
3
1832
3
1878-1953
3
1914-1918
3
1917-1963
3
1961-1963
3
1998-
3
Bombardment, 1945
3
Unification, 1990
3
-465 B.C.
2
1412-1431
2
1600-1699
2
1618-1900
2
1660-1714
2
1783-1865
2
1783-1899
2
1789-1900
2
1800-1999
2
1815-1860
2
1827-1868
2
1845-1998
2
1865-1877
2
1882-1941
2
1882-1945
2
1886-1953
2
1893-1976
2
1921-1944
2
1929-1945
2
1939 - 1945
2
1939-1967
2
1944-1991
2
1945-
2
1948-1949
2
1948-1967
2
1953-1985
2
1954-
2
more ...