In further consideration of Bohemians...
Always happy to admit when I am wrong (well, maybe not happy, but I admit my mistakes, anyway.) In the case of Bohemians, and the use of the term in relation to the Intelligentsia who frequented Pfaff's Cave, I stumbled upon an early use of "Bohemian" while searching for information about the Wide Awake Movement. In the Chicago Press & Tribune of 6 APR 1860 on page 2 col.5 is a comprehensive description of Pfaff's Cave, and the patrons of that place... a full year before Civil War erupted:
Amazing what can be found, when you're not looking