Lownds led the defense of Khe Sanh throughout the Battle of Khe Sanh, ultimately commanding over 6000 Marines at the base. Lownds was criticised by some for failing to send reinforcements to Lang Vei when it came under attack on the night of 6–7 February 1968, but he defended his decision on the basis that Khe Sanh itself was under artillery attack with a ground assault believed to be imminent and that any attempt to reinforce Lang Vei at night would be suicidal. Lownds' decision was accepted by the US command. Lownds received further criticism when he refused to allow the approximately 6000 Laotian survivors and dependents of the Lang Vei garrison into the base on the basis that it would compromise base security. These refugees were initially housed outside the base perimeter with most eventually seeking refuge further east.