Imagine you are an advisor for a sitting us president. you have just received word that three small boats appear to have attacked a us port. the president wants to retaliate, but you think more evidence is needed before us forces attack. what historical event could you reference to support your case best?

The best piece of historical evidence you could use to justify a counter attack in a situation like this would be the bombing of the USS Cole, which greatly changed the rules of engagement.

In 911, a group of vikings lead by rollo besieged paris and chartres. after a victory near chartres on 26 august, charles decided to negotiate with rollo. the talks were led by hervé, the archbishop of reims. this resulted in the treaty of saint-clair-sur-epte, which granted rollo and his soldiers all the land between the river epte and the sea. it also granted him brittany, "for his livelihood". at the time, brittany was an independent land which france had not been able to conquer. in exchange, rollo promised the king his loyalty and military assistance when needed. also rollo also agreed to be baptised and to marry gisela, the king's daughter. the territory given rollo is about the same as upper normandy.