One of the mistakes various races keep making is that the Culture, as a race of ultra-advanced hippies, are push-overs. Whenever war breaks out, however, the Culture Minds switch to tactics and warfare-based routines (not to mention converting their continent-sizes pleasure ships into battlecruisers in the bat of any eyelid) and annihilate every enemy they come into contact with. Even during peacetime the Minds maintain the Special Circumstances division to eliminate threats to the Culture before they can become too great.

The appendix to CONSIDER PHLEBAS, which shows how the Culture operates in wartime, is quite interesting.