Following the failure of the Principality of Zeon's "Operation British" to drop a colony to destroy the Earth Federal Forces' underground Jabrow headquarters in the early days of One Year War, the brass decided to pursue other avenues to destroy the South American base. One of these plans, the "Apsalus Project" developed by Ginias Sahalin, appeared to be the most feasible. It involved constructing an atmosphere/space flight-capable mobile armor driven by a Minovsky craft system which would approach Jabrow from across Earth's surface, then launch up into high orbit and destroy Jabrow with a large mega particle cannon capable of blasting through the rock protecting the underground base.

The first Apsalus unit was constructed at Zeon's Southeast Asia mobile suit factory, under the supervision of Ginias. His younger sister, Aina Sahalin, assisted with the project by serving as the Apsalus' test pilot. Built partly out of MS-06 Zaku II parts, the Apsalus incorporated a powerful generator to run its Minovsky craft system, allowing the mobile armor to float at any altitude and fly at high speeds. However, the generator's output was not enough to give the Minovsky craft system the required power to keep the Apsalus stable in the air. Although this first Apsalus unit was built only for atmospheric test flights and was not conventionally armed, its Minovsky craft system could emit a powerful energy pulse that could be used as a defensive weapon. The first Apsalus unit was heavily damaged during field tests over enemy territory, and a second unit, the Apsalus II, was constructed. Flight and combat data from these first two units would be used, along with most of the parts from the Apsalus II, to build the final version, the Apsalus III.