We are apt to say that a foreign policy is successful only when the country, or at any rate the governing class, is united behind it. In reality, every line of policy is repudiated by a section, often by an influential section, of the country concerned. A foreign minister who waited until everyone agreed with him would have no foreign policy at all.
In my opinion we learn nothing from history except the infinite variety of men's behaviour. We study it, as we listen to music or read poetry, for pleasure, not for instruction.