I'm currently reading Commander In Chief: Franklin Delano Roosevelt, His Lieutenants, and Their War by Eric Larrabee and I noticed that he draws some similarities between FDR and Lincoln in terms of how they used their generals/staff and executive power during their respective crises. I'm less familiar with the Civil War and Lincoln's generals than I am with 20th century military leaders and World War II and I was wondering if anyone could give me some more details into what Larrabee is referencing, as his statements are somewhat vague - for example, he says, "Roosevelt stretched the boundaries of executive authority (as Lincoln did)" (628) but doesn't give any evidence/context to show how Lincoln stretched those boundaries. If anyone could provide any insight on this, it would be much appreciated! Also, if you have any suggestions for further reading, I'd love to hear them!
probably the most famous case of Lincoln skirting the Constitution was when he suspended the Writ of Habeas Corpus that is the right of people being held in prison to hear the charges. He did this so he could round up suspected Copperheads in border states. His response was that he was not going to let the US die because of a principle.
There are not many other examples I can recall of Lincoln doing this. Perhaps when they confiscated runaway slaves as "contraband" of war. Another pragmatic decision.