War Does Not Solve Problems?

It's a common saying these days that 'war does not solve any problem'. It's a politically correct thing to say.

However, history is witness to Mahabharat, World War I, World War II and many other battles and wars that did solve problems. If dialog, not war is supposed to solve all problems, then why did UK, US, France not insist on having a dialog with Hitler?

Dialog can succeed only when both sides are reasonable. If one side refuses to listen to reason and wants to change the other side's views by force or terror, then war is the only last option. And there is a good possibility that it may solve the problem.

Dialog is preferred, but one can't make a sweeping statement that war does not solve any problem. Because it does, many a times.