Because at that time, The pathway to Lusittiana was a territory conquered by the Germans troop during their conflict with Great Britain in World War I.
The Germans give the warning following the international law of warfare at that time that indicates each nations should give warning to normal civilians if they intended to target a certain area.
Article 1 gives powers and limits to the congress and createthe Senate and House of Representatives; Article 2 refers to the executive branch (President and its officers) and the day to day administration of the Nation; Article 3 creates the judicial branch, with the responsibility of interpreting the Law.
Because it offers the historian an objective snapshot of the public sentiment of the time, which the cartoonist (should be) distilling for their readers, according to their feelings, for mass appeal. I say objective as it is usually very easy to decipher their subjective viewpoint according to the publication. The value of this is that it is tapping into how the masses 'feel' rather than how subjective facts can be built to form historical opinion. It becomes especially valuable prior to this century, when public sentiment is harder to garner as we were less technologically advanced.