For an official list of nicknames of Federal Civil War units, refer to "List of Synonyms of Organizations in the Volunteer Service of the United States During the Years 1861, '62, '63, '64, and '65" published by the U.S. Adjutant General's Office in 1885.

This provides a large overview of names that various U.S. Army units went by in the war. It includes sections on the different states (including U.S. troops recruited in Confederate states), as well as sections on U.S. Regulars, and on U.S. Colored Troops. It also cross-references units in several ways that helps facilitate research.

For students of Missouri, it also provides a lot of insight into troops recruited there that ended up serving in volunteer units in other states, and units recruited in other states that ended up serving in Missouri volunteer units (including whole companies from Pennsylvania, Ohio, Wisconsin, Kansas, etc....). Some interesting obscure units also crop up in Missouri listings that are virtually unknown that pique my interest--ex. Spies, Scouts, and Messengers Home Guard, and Engineer Corps of Ironton (Detailed), to name just a couple. The book also serves to lay out the evolution, by name, of many different units from early creation to final designation.

While this book provides a large listing of Missouri nicknames, but it is not comprehensive. Anyone who has culled through Civil War era Missouri newspapers knows that a variety of nicknames for local units will appear occasionally in those publications. I note that some of them that I am aware of did not make it into this book. However, the Red Rovers, which prompted this post, does appear.

In any event, here is an online link to the book in question. Very interesting....

http://ia600309.us.archive.org/28/items/listofsynonymsof00unit/listofsynonymsof00unit.pdf