The Hundred Worlds Offensive was an operation undertaken by the New Republic two months after the Battle of Jakku to capture a swath of Imperial loyalist worlds in the Inner Rim Territories that refused to abide by the Galactic Concordance. The territory was under the control of General Denis Stromark, who continued to attack New Republic space and was the self-proclaimed "Acting Grand Vizier" of the Empire. Unbeknownst to the Republic, however, Stromark was actually loyal to the mysterious Fleet Admiral Gallius Rax, and was carrying out his orders.
What was planned to be a week-long endeavor turned into a grueling campaign that lasted for months, due to Stromark's extensive preparations and tactical ability. The Imperial general initially came to the Galactic Senate's attention after his attacks in the Seswenna sector and support for a pro-Imperial uprising in the Tion Hegemony. With his forces having taken significant losses, Stromark entrenched his remaining troops in the Outer Rim Territories for a final stand against Republic.