Sentence:  And everywhere the people, or the populace, take their own government upon themselves; and open “kinglessness,” what we call "anarchy", […] is everywhere the order of the day. Such was the history, from Baltic to Mediterranean, in Italy, France, Prussia, Austria, from end to end of Europe, in those March days of 1848. Since the destruction of the old Roman Empire by <WSD>inroad</WSD> of the Northern Barbarians, I have known nothing similar. 
Meaning of the word marked with <WSD> tags:  an advance into enemy territory, an incursion, an attempted invasion