MMGG Book 6: The Mostly True Adventures of Homer P. Figg by Rodman Philbrick

From Goodreads:

Master storyteller Rodman Philbrick takes readers on a colorful journey as young Homer Figg sets off to follow his brother into the thick of the Civil War. Through a series of fascinating events, Homer's older brother has been illegally sold to the Union Army. It is up to Homer to find him and save him. Along the way, he encounters strange but real people of that era: two tricksters who steal his money, a snake-oil salesman, a hot-air balloonist, and finally, the Maine regiment who saved Little Round Top at the Battle of Gettysburg and won the war for the Union.

Why it's MIGHTY:

The storytelling, pure and simple. Homer P. Figg may not always tell the reader the truth, but we wouldn't want it any other way. This book tells a story that's heartfelt, funny, suspenseful, and enormously entertaining with a narrator you'll never forget. FYI, there are two covers to this book and neither one of them do it justice. :)