Alan Mace
Colonel Mace was a British officer with UNIT. He wanted to lead an attack against the Sontarans but the Doctor convinced him otherwise after the deaths of a squad of soldiers including Ross Jenkins. He tried to launch a nuclear attack against the Sontarans, but the Martha clone wiped out the launch codes.
Mace co-ordinated the UNIT counter offensive at the ATMOS factory. Instead of using normal weapons which could be stopped by expanding the copper bullet, he used bullets without a coating so he could attack the Sontarans. He also orders the Valiant to be used to clear the ATMOS gas. He killed Sontaran Commander Skorr with a pistol. (DW: The Sontaran Stratagem/ The Poison Sky)