Originally Posted by jduster
Keep in mind that this poll is pre-21st century.
A relevant note; otherwise, the ongoing Iraq war would be the obvious first choice.
However, under that same standard the inclusion of "killing Saddam" is contradictory, as he was eventually killed (in the XXI century).
Executing the man was probably not a mistake; destroying his country and the political stability of the Middle East in the process most definitively was.
A good case can also be made for the continuation (even if probably not the beginning) of the Afghan War.
IMHO Bay of Pigs was a blunder, not a mistake; the Korean War was neither.
And of course, the Philippines war was a quite successful imperialist campaign by the standards of the contemporary colonialism.
The Iran-Contras was both a blunder and a mistake.
Must agree with Dr R too in his superb assessment of WW1, and on the virtual consensus here about Vietnam War & related conflicts; both were colossal mistakes.
That said, the War of 1812 may have been an even bigger mistake, as the mere survival of the US may well have been at stake if a full British retaliation would have been the result of such an immense miscalculation.