So strengths for the union was. They had lots of man power in other words they had a lot of people. Another strength is that they industrialized which means they were able to get supplies quicker and faster. For then cons or weakness is that they were fighting in unknown territory. They also had lots of pressure during this war.
Strength for the south was that they knew the land. They also had skilled troops because of how different the living conditions where from the north. They focus more on tactics. Another strength was their pride they were very prideful which help them keep on fighting.
Weakness is that they where heavenly out number. Another is that they had to defend a huge amount of land. And their economy began to colapse.
Hope this helped