Why was it easy for the North to disrupt Southern transportation once the war
began?

ba geologist finds four sedimentary rock she determines that no geologic events have shifted the layers she labeles them a,b,c,dbfrom top to bottom

i believe it would influence their own way of understanding things. it shall be a foundation where they can draw or start an argument.   historians are also  scientists that  have their tools of analysis and expertise to unlock a variety of difficulties such as relationships of man, origin, politics, economy, and culture. based on facts and understanding on these areas, they may shade light to extract ideas and develop options to validate a hypothesis or debunk it.