Han Jiang, he was one of many people who left the base the moment the danger arrived. However, little people did know that he did not truly leave the base.
He was hiding the proximity base with his group, watching the battle unfolded. When the first zombie horde was cleared, he planned to go back and took over the base from Tang Shaoyang with his group.
But then, he heard there was another zombie horde coming, a bigger zombie horde. With an additional group of apes, Han Jiang canceled his plan to take over the base.
He then searched for more people and recruited them into his group.
Han Jiang and his group were one of the famous groups in the base hence he easily recruited more people into his group. When he told his plan to his people, everyone immediately agreed to his plan.
The importance of the base was absolute. Han Jiang realized that after staying in the base. It had resources that people could not get just by killing the zombies.