A member of Caledonia's ruling Jacobite Party, Davis joined up with the Gray Death Legion in 3025 on Galatea, in a meeting with Grayson Carlyle and eight other mercenaries that went on to form the original Legion. McCall was a big, friendly Caledonian, with an engaging grin, and had a fierce pride in his Terran-Scots ancestry. Often in combat, Davis would scream Gaelic curses over the combat circuit. He was one of the longest serving members of the Legion, second only to Lori Kalmar, and was immensely loyal to Grayson. At one point, McCall served as XO for the Legion, during Lori's pregnancy with her son, Alexander. Twice in his career as a mercenary McCall turned down contract offers from other mercenary units, including an offer of a battalion command. Over the years, experience and age tempered the big Scotsman's impulsiveness, making him one of the Legions strongest field commanders.
Davis McCall was killed in combat on Hesperus II in 3065, while defending the planet from an invasion force made up of the 22nd Skye Rangers, the 4th Skye Rangers, the Warships LAS Illustrious and the FCS Indefatigable. McCall died when two enemy 'Mechs, a Rakshasa and a Guillotine, destroyed his Highlander 'Mech and kicked in the cockpit.