How do you know that berliners expected a retaliatory air strike ,following that attack on poland.?

Because it was based on a military tactic called blitzkrieg or blitzkrieg it is the popular name that receives a military tactic of attack that involves an initial bombardment, followed by the use of mobile forces attacking with speed and surprise to prevent an enemy from carrying out a coherent defense. The basic principles of these types of operations were developed in the twentieth century by several nations, and adapted years after the First World War, mainly by the Wehrmacht, to incorporate weapons and modern vehicles as a method to avoid trench warfare and the war on fixed fronts in future conflicts.

a countries leader should be motivated by the common good of the country.