Be polite write diplomatically even in a declaration of war one observes the rules of politeness.

The line encapsulates a core principle of statecraft often associated with Bismarck’s “Realpolitik”: even when pursuing hard interests—up to and including armed conflict—states benefit from disciplined language and observance of diplomatic forms. Politeness here is not mere etiquette but a tool of strategy: it preserves channels for negotiation, signals control and legitimacy, and can shape how third parties judge a dispute. The quote also implies that civility can coexist with coercion; the substance may be hostile, but the presentation should remain measured to avoid unnecessary escalation and to keep future reconciliation possible.