Jo Shelby led many of their remaining troops to exile in Mexico. Price hoped to find military service under the Mexican emperor Maximilian, but this was not to be, though Maximilian did give them land for a colony near Vera Cruz. With the failure of this colony a year or so later and the overthrow and execution of Maximilian by the legitimist government of Benito Juárez, Price, Shelby and most of their men chose to return to the United States. Price's and Shelby's adventure in Mexico later became an inspiration for the John Wayne and Rock Hudson movie The Undefeated. Assessing the Army of Missouri's performance In his paper Assessing Compound Warfare During Price's Raid, written as a thesis for the U.S. Army Command and General Staff College, Major Dale E. Davis postulates that Price's Army of Missouri failed in its campaign primarily due to Price's inability to properly employ the principles of "compound warfare". This requires an inferior power to effectively utilize regular and irregular forces in concert (such as was done by the North Vietnamese and Viet Cong against the French and Americans during the Vietnam War) to defeat a superior army. Davis also blamed Price's slow rate of movement for this outcome, and the close proximity of Confederate irregulars to his regular force. Davis observes that by wasting valuable time, ammunition and men in his relatively meaningless assaults on Fort Davidson, Glasgow, Sedalia and Boonville, Price offered Union General Rosecrans time he might not otherwise have had to organize an effective response. Price, wrote Davis, ought to have used Confederate bushwackers to harass Federal formations, forcing the Unionists to disperse significant numbers of troops to pursue them over wide ranges of territory–which would have reduced the number of effectives available to fight against Price's main force. Instead Price kept many guerrillas close to his army, even incorporating some into his ranks, largely negating the value represented by their mobility and small, independent formations. This in turn allowed Union generals to ultimately concentrate a force large enough to trap and defeat Price at Westport, effectively ending his campaign and leading to the demise of the Army of Missouri. Commanders Major General Sterling Price (September 8-December 3, 1864) Major General John B. Clark, Jr. (temporary: December 3, 1864) Engagements Battle of Fort Davidson (September 27, 1864) Fourth Battle of Boonville (October 11, 1864) Battle of Glasgow (October 15, 1864)