What are the motifs in The Fate of Liberty by Mark E. Neely, Jr.?

Expediency is a recurring idea. The Fate of Liberty maintains Abraham Lincoln makes most of his decisions for expediency and, if a decision raises enough controversy, justifies it on constitutional and historical grounds. His first suspension of the writ of habeas corpus causes him angst over its legality - it never having been done in 70 years and being left in the Constitution unclear whether it falls in the provenance of the executive or legislative branch - is issued, because Marylanders have rioted and threaten to cut Washington, DC, off from the rest of the North. He has no choice but to keep the rail lines open. The order expands southward by his giving de facto recognition to orders given by local authorities. Again, it is expedient to legalize the matter.