Norman Maclean and Laird Robinson, in an attempt to forensically analyze the Mann Gulch Fire, brought together multiple sources, including the official report of the United States Forest Service of the fire, the testimony of the three men who fought the fire and lived, and the research and report of Robert Jansson and Harry T. Gisborne. Jansson was ranger of the Helena National Forest's Canyon Ferry District, the area that included Mann Gulch, on duty the day of the fire. Maclean and Laird also took Walter Rumsey and Robert Sallee, the only two living survivors of the fire team, back to the scene of the fire in 1978, hoping that walking the ground again would help solve some of the missing pieces. Additionally, Laird and Maclean would use the modern Fire Lab and their mathematical analysis, to search for answers to the fire. With all of these pieces, several trips to Mann Gulch, and ideas bantered back and forth between each other, Bud Moore, Ed Heilman, Rich Rothermel, Frank Albini, and other members of the U.S. Forest Service forest fire investigators, Maclean and Laird came to new conclusions on the fire's events: that the wind went in the opposite direction than was originally thought possible, and once the fire got started, it created its own unique weather system. It was always assumed that the wind was traveling south, or upstream, on the Missouri River at that time of day. Instead, they proved that the wind was traveling north, or downriver, and that the top of the ridge split this downriver wind in two. These two separate-smaller winds then re-converged in the heart of the gulch. This convergence combined with massive heat, produced by the fire and the hot August afternoon. Additionally, the vegetation pattern played a part in how the fire developed and took the lives of the men. The south side of the gulch was of the mountains, with taller forested trees, but the north side of the gulch was of the plains, with smaller trees and dense grasses. This combination of contrasting vegetation, heat, air currents, and right-angle winds, would cause the fire to change direction instantly, trapping and killing most of the fire fighters in its path.
