Lang was among the soldiers of Alpha-Omega, working under Colonel McCullough during the Human-Ape War. Lang was assigned to an ambush at an ape fort in the Muir Woods, with guidance from McCullough's various "donkeys", including Red. When the apes, led by Caesar counter-attacked the Alpha-Omega assault by firing arrows at the soldiers, Lang was among the four human survivors who avoided being hit.
Lang, Red, Preacher, Travis and one other human survivor were brought to Caesar. When Travis told Caesar to just kill them, Lang told him to shut up. After Caesar was done talking he had Lang and the soldiers sent back to their base of operations on horseback at the Border. Lang later accompanied McCullough and the other soldier on a mission to assassinate Caesar. While scouting the tunnels, Lang approached the large opening where Blue Eyes, Cornelia and Cornelius were hiding in their nest. As Lang moved closer, Blue Eyes tackled her down and beat her to death.