After the Destruction of Saratoga by the alien cluster, the Federation learned the alien was heading to a planet known as Glendathu when it crush the Saratoga. The Federation speculated the planet as the home planet or an advance base of the Extraterrestrial life form.
Some troopers were killed by the HE shells when they were still in the landing capsules. Those troopers who survived the drop commenced the attack immediately.
After a while, Sergeant Dan and his fellow troopers, including Pat Leivy, "Kitten" Smith, and S. Cherenkov found an assumed base of the Extraterrestrial life form — a massive cluster of the Aliens. Sergeant Dunn was once captured by the enemy, but he was saved by Juan Rico, who just witness the death of T. Azuma. Together, they attacked the cluster with various of weapons.