William E. Parrish, "Gamble, Hamilton Rowan," American National Biography Online, February 2000, http://www.anb.org/articles/04/04-00401.html.
Gamble inherited an exceedingly difficult situation in 1861 and dealt with it quite credibly. He determined from the outset to let Missourians retain as much control of their internal situation as the establishment of martial law would allow, hence his concern to have local militia cooperating with federal military authorities to try to keep order. While Gamble's relationship with the federal military commanders at St. Louis was not always harmonious because of their jealous guardianship of authority, the militia worked fairly effectively given the turbulent condition of the state. Gamble's insistence on the militia's use allowed many Missourians who would not have volunteered beyond the state's boundaries to participate in the war effort. Although determined to protect slavery at the beginning of the war, Gamble moderated that stand as it became obvious that sentiment was shifting toward some form of emancipation. He effectively steered a middle course on that issue. Throughout the war his was the voice of local control and moderation, and his leadership did much to hold Missourians together during the four years of internecine strife.