I found this quote by Winston Churchill today while doing some research:
Never, never, never believe any war will be smooth and easy, or that anyone who embarks on the strange voyage can measure the tides and hurricanes he will encounter. The statesman who yields to war fever must realize that once the signal is given, he is no longer the master of policy but the slave of unforeseeable and uncontrollable events.
British politician (1874 - 1965)
Having just passed the six-year mark celebrating our war in Iraq this past March, it strikes me how true this seems.