| Civil War poly | Civil War 0 | Civil War 1 | Civil War 2 | Civil War 3 | Civil War 4 | Civil War 5 | Civil War 6 | Civil War 7 | Civil War 8 | Civil War 9 | Richard_Nixon - | John N. Mitchell - | H. R. Haldeman - | John Ehrlichman |
| List US Wars | List lengths US participation wars | Military history US | List of conflicts US | US Declaration of war | US List military operations |
| List Ongoing Armed Conflicts | Timeline US military operations | List American Indian Wars | US military casualties | List US World War II battles | Vietnam War | Role US Vietnam War |
|
The AD/BC notation does not use a year zero; however, astronomical year numbering does use a minus sign, so '2 BC' is equal to 'year -1', '1 BC' is equal to astronomical 'year 0', and so forth. In the Gregorian system, the Nth century AD ..starts in the year (N-1)*100+1 and .. ends in year N*100, so for example, the 16th century begins on January 1, 1501 and ends December 31, 1600. However, year order is reversed in the BC era, so the Nth century BC begins in the year N*100 BC and ends in (N-1)*100+1 BC, so for example the third century BC begins in
300 BC and ends 201 BC.