What If a Single Modern Marine Fought An Entire Army?

Could one U.S. Marine with a SIG Sauer M18 pistol defeat six of history's most feared armies, one at a time, on their home soil? He otherwise carries usual gear: hard plates, helmet, eye protection, boots, a knife, a med kit, three quarts of water. Ammo's unlimited in our scenario, but the mag isn't... every reload still costs him two seconds. Made by my Last Brain Cell