No battle in American history has inspired more debate and conjecture than the one that claimed Custer's command at the Little Bighorn. Starting with the shadowy Mitch Boyer, known as the sole Army scout who followed Custer into battle and died with him, this study fills in the true details of Boyer's life preceding the Sioux campaign of 1876. His career as a guide and interpreter epitomized the advance of white Americans into Indian country, which led to the tragic encounters of that year. Part 2 of the text covers the two weeks during which Boyer served as Custer's key guide and scout. Here the focus and approach change, for the troopers and scouts separated into many parties. Numerous details of the last days, hours and seconds of the campaign, and the final action of Custer's own battalion, are clarified. Using only known primary accounts of the battle and employing topographic research in conjunction with time-motion analysis, the author attempts to produce a coherent picture of events. His method exposes accounts that are blatantly impossible and illuminates the often undervalued interviews with Indian scouts. The resulting reconstruction of the battle illuminates what really happened that day at the Little Bighorn.