The British invasion of Iceland. We have gems such as
And then they lost the element of surprise by flying an airplane over the capital city. They made a ton of wrong assumptions about the situation in Iceland. Good thing that no one bothered to actually fight, and it was entirely bloodless.
http://en.wikipedia.org/wiki/Invasion_of_Iceland
Yup. Invading a neutral country, then handing it over to another neutral country (the US before Pearl Harbor). The Astandid that resulted because of the invasion was pretty funny too.